TY  - JOUR
AU  - Bradarić, Ivica
AU  - Matić, Vladimir M.
AU  - Savić, Ilija
AU  - Rakočević, Zlatko Lj.
AU  - Popović, Maja
AU  - Destraz, Daniel
AU  - Keller, Hugo
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7907
AB  - Calcium ruthenate (CaRuO3) is widely believed to be located close to a quantum critical point due to the strong non-Fermi-liquid behavior expressed in the temperature dependence of electronic transport, specific heat, optical conductivity, etc. However, the corresponding anomalous behavior, marking crossover temperature regimes in the magnetic response of CaRuO3, is still lacking. Here we report detailed AC and DC magnetic susceptibility measurements of CaRuO3 and CaR u0.97 Ti 0.03 O3. The AC magnetic susceptibility measurements of CaRuO3 show a slight dependence on the frequency of AC magnetic field below ∼40K, and an additional subtle change of curvature around 12 K. We interpret these results as a critical slowing down of spin fluctuations towards T = 0 K. We confirm these observations by magnetic measurements of CaRu0.97 Ti 0.03 O3, which show a pronounced magnetic response corresponding to the above temperatures.
T2  - Physical Review B
T1  - Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping
VL  - 98
IS  - 13
SP  - 134436
DO  - 10.1103/PhysRevB.98.134436
ER  - 

@article{
author = "Bradarić, Ivica and Matić, Vladimir M. and Savić, Ilija and Rakočević, Zlatko Lj. and Popović, Maja and Destraz, Daniel and Keller, Hugo",
year = "2018",
abstract = "Calcium ruthenate (CaRuO3) is widely believed to be located close to a quantum critical point due to the strong non-Fermi-liquid behavior expressed in the temperature dependence of electronic transport, specific heat, optical conductivity, etc. However, the corresponding anomalous behavior, marking crossover temperature regimes in the magnetic response of CaRuO3, is still lacking. Here we report detailed AC and DC magnetic susceptibility measurements of CaRuO3 and CaR u0.97 Ti 0.03 O3. The AC magnetic susceptibility measurements of CaRuO3 show a slight dependence on the frequency of AC magnetic field below ∼40K, and an additional subtle change of curvature around 12 K. We interpret these results as a critical slowing down of spin fluctuations towards T = 0 K. We confirm these observations by magnetic measurements of CaRu0.97 Ti 0.03 O3, which show a pronounced magnetic response corresponding to the above temperatures.",
journal = "Physical Review B",
title = "Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping",
volume = "98",
number = "13",
pages = "134436",
doi = "10.1103/PhysRevB.98.134436"
}

Bradarić, I., Matić, V. M., Savić, I., Rakočević, Z. Lj., Popović, M., Destraz, D.,& Keller, H.. (2018). Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping. in Physical Review B, 98(13), 134436.
https://doi.org/10.1103/PhysRevB.98.134436

Bradarić I, Matić VM, Savić I, Rakočević ZL, Popović M, Destraz D, Keller H. Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping. in Physical Review B. 2018;98(13):134436.
doi:10.1103/PhysRevB.98.134436 .

Bradarić, Ivica, Matić, Vladimir M., Savić, Ilija, Rakočević, Zlatko Lj., Popović, Maja, Destraz, Daniel, Keller, Hugo, "Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping" in Physical Review B, 98, no. 13 (2018):134436,
https://doi.org/10.1103/PhysRevB.98.134436 . .

TY  - JOUR
AU  - Bradarić, Ivica
AU  - Matić, Vladimir M.
AU  - Savić, Ilija
AU  - Rakočević, Zlatko Lj.
AU  - Popović, Maja
AU  - Destraz, Daniel
AU  - Keller, Hugo
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7908
UR  - https://arxiv.org/abs/1712.04471
AB  - Calcium ruthenate (CaRuO3) is widely believed to be located close to a quantum critical point due to the strong non-Fermi-liquid behavior expressed in the temperature dependence of electronic transport, specific heat, optical conductivity, etc. However, the corresponding anomalous behavior, marking crossover temperature regimes in the magnetic response of CaRuO3, is still lacking. Here we report detailed AC and DC magnetic susceptibility measurements of CaRuO3 and CaR u0.97 Ti 0.03 O3. The AC magnetic susceptibility measurements of CaRuO3 show a slight dependence on the frequency of AC magnetic field below ∼40K, and an additional subtle change of curvature around 12 K. We interpret these results as a critical slowing down of spin fluctuations towards T = 0 K. We confirm these observations by magnetic measurements of CaRu0.97 Ti 0.03 O3, which show a pronounced magnetic response corresponding to the above temperatures.
T2  - Physical Review B
T1  - Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping
VL  - 98
IS  - 13
SP  - 134436
DO  - 10.1103/PhysRevB.98.134436
ER  - 

@article{
author = "Bradarić, Ivica and Matić, Vladimir M. and Savić, Ilija and Rakočević, Zlatko Lj. and Popović, Maja and Destraz, Daniel and Keller, Hugo",
year = "2018",
abstract = "Calcium ruthenate (CaRuO3) is widely believed to be located close to a quantum critical point due to the strong non-Fermi-liquid behavior expressed in the temperature dependence of electronic transport, specific heat, optical conductivity, etc. However, the corresponding anomalous behavior, marking crossover temperature regimes in the magnetic response of CaRuO3, is still lacking. Here we report detailed AC and DC magnetic susceptibility measurements of CaRuO3 and CaR u0.97 Ti 0.03 O3. The AC magnetic susceptibility measurements of CaRuO3 show a slight dependence on the frequency of AC magnetic field below ∼40K, and an additional subtle change of curvature around 12 K. We interpret these results as a critical slowing down of spin fluctuations towards T = 0 K. We confirm these observations by magnetic measurements of CaRu0.97 Ti 0.03 O3, which show a pronounced magnetic response corresponding to the above temperatures.",
journal = "Physical Review B",
title = "Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping",
volume = "98",
number = "13",
pages = "134436",
doi = "10.1103/PhysRevB.98.134436"
}

Bradarić, I., Matić, V. M., Savić, I., Rakočević, Z. Lj., Popović, M., Destraz, D.,& Keller, H.. (2018). Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping. in Physical Review B, 98(13), 134436.
https://doi.org/10.1103/PhysRevB.98.134436

Bradarić I, Matić VM, Savić I, Rakočević ZL, Popović M, Destraz D, Keller H. Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping. in Physical Review B. 2018;98(13):134436.
doi:10.1103/PhysRevB.98.134436 .

Bradarić, Ivica, Matić, Vladimir M., Savić, Ilija, Rakočević, Zlatko Lj., Popović, Maja, Destraz, Daniel, Keller, Hugo, "Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping" in Physical Review B, 98, no. 13 (2018):134436,
https://doi.org/10.1103/PhysRevB.98.134436 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
AU  - Milić, Mirjana M.
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5270
AB  - The 60 K plateau of the YBa2Cu3O6+x high-T-c superconducting compound has traditionally been known as a horizontal section in its T-c(x) characteristics within which the critical temperature maintains at a constant level T-c approximate to 60 K. However, recent experiments on a series of high quality single crystals samples of the YBa2Cu3O6+x compound (produced by improved techniques of sample preparation) have shown the 60 K plateau does not manifest itself anymore as a horizontal section of the T-c(x), but emerges as a section over which T-c(x) keeps on continuously rising (the quasi 60 K plateau). Here we propose a theoretical model that explains how the classical (horizontal) 60 K plateau naturally evolves into the quasi 60 K plateau, due to the improved orthorhombicity in the high quality single crystal material accompanied by longer CuO chains. The model assumes that short CuO chains do not contribute to the hole transfer from chains to CuO2 layers, but only chains whose length is greater than, or equal to, a certain threshold length l(cr). Our calculations point to a conclusion that this minimal number of oxygen atoms in a CuO chain, that is required to trigger the hole transfer, is equal to four. The calculated values for T-c(x) are in a very good correlation with the corresponding experimentally obtained results. (C) 2012 Elsevier B. V. All rights reserved.
T2  - Journal of Alloys and Compounds
T1  - A model for the quasi 60 K plateau in the YBa2Cu3O6+x high-T-c compound
VL  - 551
SP  - 189
EP  - 194
DO  - 10.1016/j.jallcom.2012.10.047
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ. and Milić, Mirjana M.",
year = "2013",
abstract = "The 60 K plateau of the YBa2Cu3O6+x high-T-c superconducting compound has traditionally been known as a horizontal section in its T-c(x) characteristics within which the critical temperature maintains at a constant level T-c approximate to 60 K. However, recent experiments on a series of high quality single crystals samples of the YBa2Cu3O6+x compound (produced by improved techniques of sample preparation) have shown the 60 K plateau does not manifest itself anymore as a horizontal section of the T-c(x), but emerges as a section over which T-c(x) keeps on continuously rising (the quasi 60 K plateau). Here we propose a theoretical model that explains how the classical (horizontal) 60 K plateau naturally evolves into the quasi 60 K plateau, due to the improved orthorhombicity in the high quality single crystal material accompanied by longer CuO chains. The model assumes that short CuO chains do not contribute to the hole transfer from chains to CuO2 layers, but only chains whose length is greater than, or equal to, a certain threshold length l(cr). Our calculations point to a conclusion that this minimal number of oxygen atoms in a CuO chain, that is required to trigger the hole transfer, is equal to four. The calculated values for T-c(x) are in a very good correlation with the corresponding experimentally obtained results. (C) 2012 Elsevier B. V. All rights reserved.",
journal = "Journal of Alloys and Compounds",
title = "A model for the quasi 60 K plateau in the YBa2Cu3O6+x high-T-c compound",
volume = "551",
pages = "189-194",
doi = "10.1016/j.jallcom.2012.10.047"
}

Matić, V. M., Lazarov, N. Đ.,& Milić, M. M.. (2013). A model for the quasi 60 K plateau in the YBa2Cu3O6+x high-T-c compound. in Journal of Alloys and Compounds, 551, 189-194.
https://doi.org/10.1016/j.jallcom.2012.10.047

Matić VM, Lazarov NĐ, Milić MM. A model for the quasi 60 K plateau in the YBa2Cu3O6+x high-T-c compound. in Journal of Alloys and Compounds. 2013;551:189-194.
doi:10.1016/j.jallcom.2012.10.047 .

Matić, Vladimir M., Lazarov, Nenad Đ., Milić, Mirjana M., "A model for the quasi 60 K plateau in the YBa2Cu3O6+x high-T-c compound" in Journal of Alloys and Compounds, 551 (2013):189-194,
https://doi.org/10.1016/j.jallcom.2012.10.047 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4706
AB  - A model has been proposed to calculate the p(x) and T-c(x) dependences in the Y1-b(Ca)(b)Ba2Cu3O6+x high-T-c cuprate family and applied to b = 0, b = 0.1, and b = 0.2 cases, for which experimental data exist in the literature. The results obtained imply that the Ca efficiency to provide holes is independent of the basal plane oxygen concentration, which is consistent with a view that electrons from CuO2 layers would go primarily to Ca since it is twice closer than oxygen (in addition, the chain oxygen is screened by a layer made up of Ba and O(4) ions). It is shown that, in fully oxygenized compounds (x = 1) the average efficiency, chi, of a chain oxygen to attract an electron from the two nearby layers is reduced by the Ca insertion, though not because the charge transfer mechanism is in itself weakened by Ca, but because a part of electrons that are otherwise available in CuO2 layers has already been removed by the substitution of Y3+ with Ca2+. It has been found that the b-dependence of the average oxygen doping efficiency can be fairly accurately described by the following relation: chi(b) = 0.39 x (1 - 0.786). The calculated p(x) and T-c(x) dependences are in very good agreement with the available experimental data. (C) 2011 Elsevier Ltd. All rights reserved.
T2  - Solid State Communications
T1  - p(x) and T-c(x) characteristics in the Y1-b(Ca)(b)Ba2Cu3O6+x cuprate family
VL  - 152
IS  - 4
SP  - 307
EP  - 310
DO  - 10.1016/j.ssc.2011.11.021
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ.",
year = "2012",
abstract = "A model has been proposed to calculate the p(x) and T-c(x) dependences in the Y1-b(Ca)(b)Ba2Cu3O6+x high-T-c cuprate family and applied to b = 0, b = 0.1, and b = 0.2 cases, for which experimental data exist in the literature. The results obtained imply that the Ca efficiency to provide holes is independent of the basal plane oxygen concentration, which is consistent with a view that electrons from CuO2 layers would go primarily to Ca since it is twice closer than oxygen (in addition, the chain oxygen is screened by a layer made up of Ba and O(4) ions). It is shown that, in fully oxygenized compounds (x = 1) the average efficiency, chi, of a chain oxygen to attract an electron from the two nearby layers is reduced by the Ca insertion, though not because the charge transfer mechanism is in itself weakened by Ca, but because a part of electrons that are otherwise available in CuO2 layers has already been removed by the substitution of Y3+ with Ca2+. It has been found that the b-dependence of the average oxygen doping efficiency can be fairly accurately described by the following relation: chi(b) = 0.39 x (1 - 0.786). The calculated p(x) and T-c(x) dependences are in very good agreement with the available experimental data. (C) 2011 Elsevier Ltd. All rights reserved.",
journal = "Solid State Communications",
title = "p(x) and T-c(x) characteristics in the Y1-b(Ca)(b)Ba2Cu3O6+x cuprate family",
volume = "152",
number = "4",
pages = "307-310",
doi = "10.1016/j.ssc.2011.11.021"
}

Matić, V. M.,& Lazarov, N. Đ.. (2012). p(x) and T-c(x) characteristics in the Y1-b(Ca)(b)Ba2Cu3O6+x cuprate family. in Solid State Communications, 152(4), 307-310.
https://doi.org/10.1016/j.ssc.2011.11.021

Matić VM, Lazarov NĐ. p(x) and T-c(x) characteristics in the Y1-b(Ca)(b)Ba2Cu3O6+x cuprate family. in Solid State Communications. 2012;152(4):307-310.
doi:10.1016/j.ssc.2011.11.021 .

Matić, Vladimir M., Lazarov, Nenad Đ., "p(x) and T-c(x) characteristics in the Y1-b(Ca)(b)Ba2Cu3O6+x cuprate family" in Solid State Communications, 152, no. 4 (2012):307-310,
https://doi.org/10.1016/j.ssc.2011.11.021 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
AU  - Milić, Mirjana M.
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5155
AB  - A model for the chain-to-plane charge transfer is proposed to account for the two plateaus, at 60 K and at 90 K, of the T-c(x) characteristics of the YBa2Cu3O6+x high-T-c superconductor. It is assumed that the number of holes transferred from a CuO chain of length l to two nearby CuO2 sheets is proportional to l (that is, to the number of oxygen atoms in the chain), if the chain length is greater than, or equal to, a certain critical chain length, l(cr), that is required to trigger the charge transfer process. No holes are assumed to have been transferred from chains of length l LT l(cr). The calculated T-c(x) dependence is found to be in excellent agreement with the experimentally reported T-c(x). The critical chain length parameter is estimated to be equal to l(cr) = 11 (eleven oxygen atoms in a chain), which is a greater value than that obtained in the previously proposed model for the chain-to-plane charge transfer (l(cr) = 4). The results obtained out of the proposed model are briefly discussed.
T2  - Chinese Physics B
T1  - A model for the chain-to-plane charge transfer in YBa2Cu3O6+x
VL  - 21
IS  - 11
DO  - 10.1088/1674-1056/21/11/117401
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ. and Milić, Mirjana M.",
year = "2012",
abstract = "A model for the chain-to-plane charge transfer is proposed to account for the two plateaus, at 60 K and at 90 K, of the T-c(x) characteristics of the YBa2Cu3O6+x high-T-c superconductor. It is assumed that the number of holes transferred from a CuO chain of length l to two nearby CuO2 sheets is proportional to l (that is, to the number of oxygen atoms in the chain), if the chain length is greater than, or equal to, a certain critical chain length, l(cr), that is required to trigger the charge transfer process. No holes are assumed to have been transferred from chains of length l LT l(cr). The calculated T-c(x) dependence is found to be in excellent agreement with the experimentally reported T-c(x). The critical chain length parameter is estimated to be equal to l(cr) = 11 (eleven oxygen atoms in a chain), which is a greater value than that obtained in the previously proposed model for the chain-to-plane charge transfer (l(cr) = 4). The results obtained out of the proposed model are briefly discussed.",
journal = "Chinese Physics B",
title = "A model for the chain-to-plane charge transfer in YBa2Cu3O6+x",
volume = "21",
number = "11",
doi = "10.1088/1674-1056/21/11/117401"
}

Matić, V. M., Lazarov, N. Đ.,& Milić, M. M.. (2012). A model for the chain-to-plane charge transfer in YBa2Cu3O6+x. in Chinese Physics B, 21(11).
https://doi.org/10.1088/1674-1056/21/11/117401

Matić VM, Lazarov NĐ, Milić MM. A model for the chain-to-plane charge transfer in YBa2Cu3O6+x. in Chinese Physics B. 2012;21(11).
doi:10.1088/1674-1056/21/11/117401 .

Matić, Vladimir M., Lazarov, Nenad Đ., Milić, Mirjana M., "A model for the chain-to-plane charge transfer in YBa2Cu3O6+x" in Chinese Physics B, 21, no. 11 (2012),
https://doi.org/10.1088/1674-1056/21/11/117401 . .

TY  - JOUR
AU  - Milić, Mirjana M.
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
PY  - 2011
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4227
AB  - An extended ASYNNNI model, that beside nearest-neighbour and next-nearest neighbour O-O interactions in the basal plane also includes interactions between the three nearest oxygen atoms, is used to describe the statistics of CuO chain fragmentation and to calculate doping and T (c) in YBa2Cu3O6+x . Calculations were made by the Monte Carlo method employing the recently proposed charge transfer model that assumes only chains whose length is equal to, or exceeds, a characteristic (critical) length, l (cr) , can provide holes to the layers and contribute to doping p. The obtained p(x) is then combined with a universal T (c) versus p relation to yield T (c) (x) characteristics that correlate remarkably with those reported in recent experiments. The best coordination between theoretical and experimental T (c) (x) characteristics has been achieved for l (cr) = 2, implying that only isolated basal plane oxygen atoms (trivial chains) do not contribute holes to CuO2 layers.
T2  - Central European Journal of Physics
T1  - The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model
VL  - 9
IS  - 3
SP  - 690
EP  - 697
DO  - 10.2478/s11534-010-0060-6
ER  - 

@article{
author = "Milić, Mirjana M. and Matić, Vladimir M. and Lazarov, Nenad Đ.",
year = "2011",
abstract = "An extended ASYNNNI model, that beside nearest-neighbour and next-nearest neighbour O-O interactions in the basal plane also includes interactions between the three nearest oxygen atoms, is used to describe the statistics of CuO chain fragmentation and to calculate doping and T (c) in YBa2Cu3O6+x . Calculations were made by the Monte Carlo method employing the recently proposed charge transfer model that assumes only chains whose length is equal to, or exceeds, a characteristic (critical) length, l (cr) , can provide holes to the layers and contribute to doping p. The obtained p(x) is then combined with a universal T (c) versus p relation to yield T (c) (x) characteristics that correlate remarkably with those reported in recent experiments. The best coordination between theoretical and experimental T (c) (x) characteristics has been achieved for l (cr) = 2, implying that only isolated basal plane oxygen atoms (trivial chains) do not contribute holes to CuO2 layers.",
journal = "Central European Journal of Physics",
title = "The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model",
volume = "9",
number = "3",
pages = "690-697",
doi = "10.2478/s11534-010-0060-6"
}

Milić, M. M., Matić, V. M.,& Lazarov, N. Đ.. (2011). The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model. in Central European Journal of Physics, 9(3), 690-697.
https://doi.org/10.2478/s11534-010-0060-6

Milić MM, Matić VM, Lazarov NĐ. The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model. in Central European Journal of Physics. 2011;9(3):690-697.
doi:10.2478/s11534-010-0060-6 .

Milić, Mirjana M., Matić, Vladimir M., Lazarov, Nenad Đ., "The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model" in Central European Journal of Physics, 9, no. 3 (2011):690-697,
https://doi.org/10.2478/s11534-010-0060-6 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
AU  - Bradarić, Ivica
PY  - 2008
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3463
AB  - We propose a model for the charge transfer mechanism in Y0.8(Ca)0.2Ba2Cu3O6+x to count the hole doping of CuO2 planes and the x dependence of the critical transition temperature Tc. It is assumed that the total number of doped holes in the planes is the sum of the numbers of holes that are introduced through two separate channels: substitution of Y3+ by Ca2+ and from CuO chains that are longer than a minimal (critical) length lmin needed for charge transfer to take place. The Tc(x) dependence is obtained by combining the calculated x dependence of doping, p(x), and the universal Tc versus p relation. Although calculated Tc(x) dependences for lmin = 3 and 4 both correlate remarkably well with the experimental Tc(x), we argue that the value lmin = 3 gives a reasonable overall agreement.
T2  - Superconductor Science and Technology
T1  - Charge transfer mechanism and T-c(x) dependence in Y-0.8(Ca)(0.2)Ba2Cu3O6+x
VL  - 21
IS  - 7
SP  - 075012
DO  - 10.1088/0953-2048/21/7/075012
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ. and Bradarić, Ivica",
year = "2008",
abstract = "We propose a model for the charge transfer mechanism in Y0.8(Ca)0.2Ba2Cu3O6+x to count the hole doping of CuO2 planes and the x dependence of the critical transition temperature Tc. It is assumed that the total number of doped holes in the planes is the sum of the numbers of holes that are introduced through two separate channels: substitution of Y3+ by Ca2+ and from CuO chains that are longer than a minimal (critical) length lmin needed for charge transfer to take place. The Tc(x) dependence is obtained by combining the calculated x dependence of doping, p(x), and the universal Tc versus p relation. Although calculated Tc(x) dependences for lmin = 3 and 4 both correlate remarkably well with the experimental Tc(x), we argue that the value lmin = 3 gives a reasonable overall agreement.",
journal = "Superconductor Science and Technology",
title = "Charge transfer mechanism and T-c(x) dependence in Y-0.8(Ca)(0.2)Ba2Cu3O6+x",
volume = "21",
number = "7",
pages = "075012",
doi = "10.1088/0953-2048/21/7/075012"
}

Matić, V. M., Lazarov, N. Đ.,& Bradarić, I.. (2008). Charge transfer mechanism and T-c(x) dependence in Y-0.8(Ca)(0.2)Ba2Cu3O6+x. in Superconductor Science and Technology, 21(7), 075012.
https://doi.org/10.1088/0953-2048/21/7/075012

Matić VM, Lazarov NĐ, Bradarić I. Charge transfer mechanism and T-c(x) dependence in Y-0.8(Ca)(0.2)Ba2Cu3O6+x. in Superconductor Science and Technology. 2008;21(7):075012.
doi:10.1088/0953-2048/21/7/075012 .

Matić, Vladimir M., Lazarov, Nenad Đ., Bradarić, Ivica, "Charge transfer mechanism and T-c(x) dependence in Y-0.8(Ca)(0.2)Ba2Cu3O6+x" in Superconductor Science and Technology, 21, no. 7 (2008):075012,
https://doi.org/10.1088/0953-2048/21/7/075012 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
PY  - 2007
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3195
AB  - A model of charge transfer mechanism from CuO chains to CuO2 planes has been proposed to account for doping of the planes, assuming that only chains containing more than three oxygen atoms can contribute to hole transfer. Only chains with l GT 4 are assumed to have transferred a certain fraction, approximately 40%, of the holes created by oxygen added to the chain beyond the first three oxygen atoms. Using the so obtained x dependence of doping, p(x), at constant (room) temperature and utilizing empirical parabolic phase relation T,(p) (T-c(P) = T-c,max[1 - 82.6(p(x) - 0.16)(2)]), the T-c versus x dependence is found to have two clearly distinguished plateaus at 60 and 90 K, remarkably fitting to experimental Tc(x). The effect of statistics of CuO chain fragmentation has been included by applying cluster variation method to two dimensional asymmetric next-nearest-neighbor Ising model that is employed to describe oxygen-chain ordering in basal planes. The obtained results indicate that plateaus, coinciding with T(c)(x) = 0, emerge either when p(x) = 0 (p(x) approximate to const), in the region of OH phase formation (the 60 K plateau), or when p = 0.16, representing the optimal doping at x approximate to 0.91 in OII phase (the 90 K plateau). (c) 2007 Elsevier Ltd. All rights reserved.
T2  - Solid State Communications
T1  - Impact of chain fragmentation on charge transfer scenario and two-plateaus-like behavior of T-c(x) in YBa2Cu3O6+x
VL  - 142
IS  - 3
SP  - 165
EP  - 168
DO  - 10.1016/j.ssc.2007.01.041
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ.",
year = "2007",
abstract = "A model of charge transfer mechanism from CuO chains to CuO2 planes has been proposed to account for doping of the planes, assuming that only chains containing more than three oxygen atoms can contribute to hole transfer. Only chains with l GT 4 are assumed to have transferred a certain fraction, approximately 40%, of the holes created by oxygen added to the chain beyond the first three oxygen atoms. Using the so obtained x dependence of doping, p(x), at constant (room) temperature and utilizing empirical parabolic phase relation T,(p) (T-c(P) = T-c,max[1 - 82.6(p(x) - 0.16)(2)]), the T-c versus x dependence is found to have two clearly distinguished plateaus at 60 and 90 K, remarkably fitting to experimental Tc(x). The effect of statistics of CuO chain fragmentation has been included by applying cluster variation method to two dimensional asymmetric next-nearest-neighbor Ising model that is employed to describe oxygen-chain ordering in basal planes. The obtained results indicate that plateaus, coinciding with T(c)(x) = 0, emerge either when p(x) = 0 (p(x) approximate to const), in the region of OH phase formation (the 60 K plateau), or when p = 0.16, representing the optimal doping at x approximate to 0.91 in OII phase (the 90 K plateau). (c) 2007 Elsevier Ltd. All rights reserved.",
journal = "Solid State Communications",
title = "Impact of chain fragmentation on charge transfer scenario and two-plateaus-like behavior of T-c(x) in YBa2Cu3O6+x",
volume = "142",
number = "3",
pages = "165-168",
doi = "10.1016/j.ssc.2007.01.041"
}

Matić, V. M.,& Lazarov, N. Đ.. (2007). Impact of chain fragmentation on charge transfer scenario and two-plateaus-like behavior of T-c(x) in YBa2Cu3O6+x. in Solid State Communications, 142(3), 165-168.
https://doi.org/10.1016/j.ssc.2007.01.041

Matić VM, Lazarov NĐ. Impact of chain fragmentation on charge transfer scenario and two-plateaus-like behavior of T-c(x) in YBa2Cu3O6+x. in Solid State Communications. 2007;142(3):165-168.
doi:10.1016/j.ssc.2007.01.041 .

Matić, Vladimir M., Lazarov, Nenad Đ., "Impact of chain fragmentation on charge transfer scenario and two-plateaus-like behavior of T-c(x) in YBa2Cu3O6+x" in Solid State Communications, 142, no. 3 (2007):165-168,
https://doi.org/10.1016/j.ssc.2007.01.041 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
PY  - 2007
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3234
AB  - A model for the charge transfer mechanism in YBa(2)Cu(3)O(6+x) high-T(c) cuprate based on the critical chain length concept is proposed to account for the 60 and 90 K plateaus in the T(c)(x) dependence. It has been shown that, when the statistics of CuO chain formation was described in terms of the two-dimensional asymmetric next-to-nearest neighbor Ising (ASYNNNI) model, at any constant temperature below the top of ortho-II phase there exists a uniquely defined value of critical chain length l(cr)(T) that yields a constant doping p(x) approximate to const over the regime of ortho-II phase (related to the 60 K plateau of T(c)(x)), while the 90 K plateau coincides with the monotonically increasing p(x) over the optimal doping level p = 0.16 in the regime of the ortho-I phase. Short length chains (l LT l(cr)(T)), together with the first l(cr)(T)-2 holes in longer chains (l GT = l(cr)(T)), are taken as not capable of attracting electrons from CuO(2) planes. It is shown that only a part (approximate to 41%) of the remaining l - l(cr)(T)+1 holes in the long chains can capture electrons. The results obtained indicate that the ASYNNNI model and two-plateau-like behavior of T(c)(x) in YBa(2)Cu(3)O(6+x) are closely connected.
T2  - Journal of Physics: Condensed Matter
T1  - The origin of the 60 K plateau in YBa(2)Cu(3)O(6+x)
VL  - 19
IS  - 34
DO  - 10.1088/0953-8984/19/34/346230
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ.",
year = "2007",
abstract = "A model for the charge transfer mechanism in YBa(2)Cu(3)O(6+x) high-T(c) cuprate based on the critical chain length concept is proposed to account for the 60 and 90 K plateaus in the T(c)(x) dependence. It has been shown that, when the statistics of CuO chain formation was described in terms of the two-dimensional asymmetric next-to-nearest neighbor Ising (ASYNNNI) model, at any constant temperature below the top of ortho-II phase there exists a uniquely defined value of critical chain length l(cr)(T) that yields a constant doping p(x) approximate to const over the regime of ortho-II phase (related to the 60 K plateau of T(c)(x)), while the 90 K plateau coincides with the monotonically increasing p(x) over the optimal doping level p = 0.16 in the regime of the ortho-I phase. Short length chains (l LT l(cr)(T)), together with the first l(cr)(T)-2 holes in longer chains (l GT = l(cr)(T)), are taken as not capable of attracting electrons from CuO(2) planes. It is shown that only a part (approximate to 41%) of the remaining l - l(cr)(T)+1 holes in the long chains can capture electrons. The results obtained indicate that the ASYNNNI model and two-plateau-like behavior of T(c)(x) in YBa(2)Cu(3)O(6+x) are closely connected.",
journal = "Journal of Physics: Condensed Matter",
title = "The origin of the 60 K plateau in YBa(2)Cu(3)O(6+x)",
volume = "19",
number = "34",
doi = "10.1088/0953-8984/19/34/346230"
}

Matić, V. M.,& Lazarov, N. Đ.. (2007). The origin of the 60 K plateau in YBa(2)Cu(3)O(6+x). in Journal of Physics: Condensed Matter, 19(34).
https://doi.org/10.1088/0953-8984/19/34/346230

Matić VM, Lazarov NĐ. The origin of the 60 K plateau in YBa(2)Cu(3)O(6+x). in Journal of Physics: Condensed Matter. 2007;19(34).
doi:10.1088/0953-8984/19/34/346230 .

Matić, Vladimir M., Lazarov, Nenad Đ., "The origin of the 60 K plateau in YBa(2)Cu(3)O(6+x)" in Journal of Physics: Condensed Matter, 19, no. 34 (2007),
https://doi.org/10.1088/0953-8984/19/34/346230 . .

TY  - JOUR
AU  - Lazarov, Nenad Đ.
AU  - Spasojević, Vojislav
AU  - Matić, Vladimir M.
AU  - Kusigerski, Vladan
AU  - Guillot, Maurice
PY  - 2007
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3493
AB  - Magnetic properties of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2)center dot 3H(2)O have been studied from the magnetization data obtained in the high magnetic field-low temperature experiments (B LT = 20 T, 2.2 K LT = T LT = 29 K). An excellent agreement between experimental and calculated data for all experimental temperatures was achieved within the framework of the isolated Ning Co(II) pairs in the ground state, where each cobalt ion from the pair was situated in a differently distorted octahedral environment (asymmetric dimer). The obtained values for g-factors (g(a) and g(b)), and for the intracluster exchange integral J/k(B) = (-16.0 +/- 0.5) K confirm both the previous results on the crystal structure of the complex under consideration and the assumption on the strong antiferromagnetic coupling between cobalt ions realized by the superexchange interaction over the asymmetric oxalato bridge.
T2  - Revue Roumaine de Chimie
T1  - Magnetic properties of asymmetric Co(II) dimer at low temperatures
VL  - 52
IS  - 11
SP  - 1027
EP  - 1031
UR  - https://hdl.handle.net/21.15107/rcub_vinar_3493
ER  - 

@article{
author = "Lazarov, Nenad Đ. and Spasojević, Vojislav and Matić, Vladimir M. and Kusigerski, Vladan and Guillot, Maurice",
year = "2007",
abstract = "Magnetic properties of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2)center dot 3H(2)O have been studied from the magnetization data obtained in the high magnetic field-low temperature experiments (B LT = 20 T, 2.2 K LT = T LT = 29 K). An excellent agreement between experimental and calculated data for all experimental temperatures was achieved within the framework of the isolated Ning Co(II) pairs in the ground state, where each cobalt ion from the pair was situated in a differently distorted octahedral environment (asymmetric dimer). The obtained values for g-factors (g(a) and g(b)), and for the intracluster exchange integral J/k(B) = (-16.0 +/- 0.5) K confirm both the previous results on the crystal structure of the complex under consideration and the assumption on the strong antiferromagnetic coupling between cobalt ions realized by the superexchange interaction over the asymmetric oxalato bridge.",
journal = "Revue Roumaine de Chimie",
title = "Magnetic properties of asymmetric Co(II) dimer at low temperatures",
volume = "52",
number = "11",
pages = "1027-1031",
url = "https://hdl.handle.net/21.15107/rcub_vinar_3493"
}

Lazarov, N. Đ., Spasojević, V., Matić, V. M., Kusigerski, V.,& Guillot, M.. (2007). Magnetic properties of asymmetric Co(II) dimer at low temperatures. in Revue Roumaine de Chimie, 52(11), 1027-1031.
https://hdl.handle.net/21.15107/rcub_vinar_3493

Lazarov NĐ, Spasojević V, Matić VM, Kusigerski V, Guillot M. Magnetic properties of asymmetric Co(II) dimer at low temperatures. in Revue Roumaine de Chimie. 2007;52(11):1027-1031.
https://hdl.handle.net/21.15107/rcub_vinar_3493 .

Lazarov, Nenad Đ., Spasojević, Vojislav, Matić, Vladimir M., Kusigerski, Vladan, Guillot, Maurice, "Magnetic properties of asymmetric Co(II) dimer at low temperatures" in Revue Roumaine de Chimie, 52, no. 11 (2007):1027-1031,
https://hdl.handle.net/21.15107/rcub_vinar_3493 .

TY  - JOUR
AU  - Milić, Mirjana M.
AU  - Lazarov, Nenad Đ.
AU  - Matić, Vladimir M.
PY  - 2007
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6702
AB  - According to the charge transfer model of Kudinov et a]. the photoinduced enhancement of conductivity in YBa2Cu3O6+x material can be explained by the photoexcitation of electron-hole pairs, and the subsequent transfer of electrons to the oxygen deficient CuOx planes where they become trapped in the CuO chain fragments, while the holes remain free in the superconducting CUO2 planes contributing to the superconducting current. In this paper we have employed the numerical cluster variation method (CVM) and the recently established relation between chain probability distribution p(n) and the average chain length n(av), to calculate the number of electrons being captured in the unoccupied p orbitals of O- ions incorporated in the CuO chains, thus producing the free holes in the CUO2 planes. Our results support the standing that several processes make contribution to the effects of persistent photoconductivity and photoinduced superconductivity. (C) 2007 Elsevier B.V. All rights reserved.
T2  - Physica. C: Superconductivity and Its Applications
T1  - Cluster variation method investigation of photoinduced charge transfer in YBa2Cu3O6+x material
VL  - 460
SP  - 364
EP  - 365
DO  - 10.1016/j.physc.2007.03.051
ER  - 

@article{
author = "Milić, Mirjana M. and Lazarov, Nenad Đ. and Matić, Vladimir M.",
year = "2007",
abstract = "According to the charge transfer model of Kudinov et a]. the photoinduced enhancement of conductivity in YBa2Cu3O6+x material can be explained by the photoexcitation of electron-hole pairs, and the subsequent transfer of electrons to the oxygen deficient CuOx planes where they become trapped in the CuO chain fragments, while the holes remain free in the superconducting CUO2 planes contributing to the superconducting current. In this paper we have employed the numerical cluster variation method (CVM) and the recently established relation between chain probability distribution p(n) and the average chain length n(av), to calculate the number of electrons being captured in the unoccupied p orbitals of O- ions incorporated in the CuO chains, thus producing the free holes in the CUO2 planes. Our results support the standing that several processes make contribution to the effects of persistent photoconductivity and photoinduced superconductivity. (C) 2007 Elsevier B.V. All rights reserved.",
journal = "Physica. C: Superconductivity and Its Applications",
title = "Cluster variation method investigation of photoinduced charge transfer in YBa2Cu3O6+x material",
volume = "460",
pages = "364-365",
doi = "10.1016/j.physc.2007.03.051"
}

Milić, M. M., Lazarov, N. Đ.,& Matić, V. M.. (2007). Cluster variation method investigation of photoinduced charge transfer in YBa2Cu3O6+x material. in Physica. C: Superconductivity and Its Applications, 460, 364-365.
https://doi.org/10.1016/j.physc.2007.03.051

Milić MM, Lazarov NĐ, Matić VM. Cluster variation method investigation of photoinduced charge transfer in YBa2Cu3O6+x material. in Physica. C: Superconductivity and Its Applications. 2007;460:364-365.
doi:10.1016/j.physc.2007.03.051 .

Milić, Mirjana M., Lazarov, Nenad Đ., Matić, Vladimir M., "Cluster variation method investigation of photoinduced charge transfer in YBa2Cu3O6+x material" in Physica. C: Superconductivity and Its Applications, 460 (2007):364-365,
https://doi.org/10.1016/j.physc.2007.03.051 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
PY  - 2006
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3061
AB  - Statistics of CuO chains in basal planes of YBa2Cu3O6+x high-T-c superconductor has been studied in terms of two dimensional asymmetric next-to-nearest-neighbor Ising (ASYNNNI) model, with accentuation on distribution of CuO, chains per different chain lengths. It has been shown that the fraction p(1) of CuO chains containing l oxygen ions (i.e., having the length equal to l), satisfies so-called law of geometric distribution p(l) = w(1-w)(l-1), where the quantity w is equal to the inverse of average chain length l(av) in the system, for given values of oxygen content x and temperature T. In the case of ortho-II (OII) structural phase, the geometric chain probability distribution is shown to hold separately for each of two different sublattices of oxygen sites, commonly known as alpha(1), and alpha(2), with respectively defined l(av)(alpha 1)(x, T) and l(av)(alpha 2)(x, T). The theoretically derived result of the chain probability distribution p(l) is shown to be in a remarkable agreement with the results obtained out of extensive Monte Carlo calculations that were made within region of stability of orthorhombic structural phases in (x, 7) space. The relevance of chain length distribution for accurate count of the number of transferred electronic holes to superconducting CuO2 layers has been pointed out and expression for hole concentration has been derived. The concept of critical chain length for charge transfer mechanism was briefly discussed. (c) 2006 Elsevier B.V. All rights reserved.
T2  - Physica. C: Superconductivity and Its Applications
T1  - Geometric distribution of CuO chains in YBa2Cu3O6+x
VL  - 443
IS  - 1-2
SP  - 49
EP  - 56
DO  - 10.1016/j.physc.2006.04.094
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ.",
year = "2006",
abstract = "Statistics of CuO chains in basal planes of YBa2Cu3O6+x high-T-c superconductor has been studied in terms of two dimensional asymmetric next-to-nearest-neighbor Ising (ASYNNNI) model, with accentuation on distribution of CuO, chains per different chain lengths. It has been shown that the fraction p(1) of CuO chains containing l oxygen ions (i.e., having the length equal to l), satisfies so-called law of geometric distribution p(l) = w(1-w)(l-1), where the quantity w is equal to the inverse of average chain length l(av) in the system, for given values of oxygen content x and temperature T. In the case of ortho-II (OII) structural phase, the geometric chain probability distribution is shown to hold separately for each of two different sublattices of oxygen sites, commonly known as alpha(1), and alpha(2), with respectively defined l(av)(alpha 1)(x, T) and l(av)(alpha 2)(x, T). The theoretically derived result of the chain probability distribution p(l) is shown to be in a remarkable agreement with the results obtained out of extensive Monte Carlo calculations that were made within region of stability of orthorhombic structural phases in (x, 7) space. The relevance of chain length distribution for accurate count of the number of transferred electronic holes to superconducting CuO2 layers has been pointed out and expression for hole concentration has been derived. The concept of critical chain length for charge transfer mechanism was briefly discussed. (c) 2006 Elsevier B.V. All rights reserved.",
journal = "Physica. C: Superconductivity and Its Applications",
title = "Geometric distribution of CuO chains in YBa2Cu3O6+x",
volume = "443",
number = "1-2",
pages = "49-56",
doi = "10.1016/j.physc.2006.04.094"
}

Matić, V. M.,& Lazarov, N. Đ.. (2006). Geometric distribution of CuO chains in YBa2Cu3O6+x. in Physica. C: Superconductivity and Its Applications, 443(1-2), 49-56.
https://doi.org/10.1016/j.physc.2006.04.094

Matić VM, Lazarov NĐ. Geometric distribution of CuO chains in YBa2Cu3O6+x. in Physica. C: Superconductivity and Its Applications. 2006;443(1-2):49-56.
doi:10.1016/j.physc.2006.04.094 .

Matić, Vladimir M., Lazarov, Nenad Đ., "Geometric distribution of CuO chains in YBa2Cu3O6+x" in Physica. C: Superconductivity and Its Applications, 443, no. 1-2 (2006):49-56,
https://doi.org/10.1016/j.physc.2006.04.094 . .

TY  - CONF
AU  - Milić, Mirjana M.
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
PY  - 2006
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9458
AB  - The number of positive holes transferred from the CuOx basal planes to the superconducting CuO2 planes of YBa2Cu3O6+x material was calculated as a function of oxygen content x, by the use of numerical cluster variation method (CVM). The calculations were performed for the set of three different temperatures and for the different values of the parameter ξl which represents the ratio of the number m of divalent oxygen ions in the chain fragment and the total number l of oxygen ions in the chain fragment. The obtained hole count versus x dependence showed no plateau behavior for low temperatures (t=0.25 and t=0.35) while for t=0.45 indication of plateau behavior is present.
PB  - Society of Physical Chemists of Serbia
C3  - Physical chemistry 2006: 8th international conference on fundemental and applied aspract of physical chemistry
T1  - Cvm study of charge transfer in YBa2Cu3O6+x material
SP  - 570
EP  - 572
UR  - https://hdl.handle.net/21.15107/rcub_vinar_9458
ER  - 

@conference{
author = "Milić, Mirjana M. and Matić, Vladimir M. and Lazarov, Nenad Đ.",
year = "2006",
abstract = "The number of positive holes transferred from the CuOx basal planes to the superconducting CuO2 planes of YBa2Cu3O6+x material was calculated as a function of oxygen content x, by the use of numerical cluster variation method (CVM). The calculations were performed for the set of three different temperatures and for the different values of the parameter ξl which represents the ratio of the number m of divalent oxygen ions in the chain fragment and the total number l of oxygen ions in the chain fragment. The obtained hole count versus x dependence showed no plateau behavior for low temperatures (t=0.25 and t=0.35) while for t=0.45 indication of plateau behavior is present.",
publisher = "Society of Physical Chemists of Serbia",
journal = "Physical chemistry 2006: 8th international conference on fundemental and applied aspract of physical chemistry",
title = "Cvm study of charge transfer in YBa2Cu3O6+x material",
pages = "570-572",
url = "https://hdl.handle.net/21.15107/rcub_vinar_9458"
}

Milić, M. M., Matić, V. M.,& Lazarov, N. Đ.. (2006). Cvm study of charge transfer in YBa2Cu3O6+x material. in Physical chemistry 2006: 8th international conference on fundemental and applied aspract of physical chemistry
Society of Physical Chemists of Serbia., 570-572.
https://hdl.handle.net/21.15107/rcub_vinar_9458

Milić MM, Matić VM, Lazarov NĐ. Cvm study of charge transfer in YBa2Cu3O6+x material. in Physical chemistry 2006: 8th international conference on fundemental and applied aspract of physical chemistry. 2006;:570-572.
https://hdl.handle.net/21.15107/rcub_vinar_9458 .

Milić, Mirjana M., Matić, Vladimir M., Lazarov, Nenad Đ., "Cvm study of charge transfer in YBa2Cu3O6+x material" in Physical chemistry 2006: 8th international conference on fundemental and applied aspract of physical chemistry (2006):570-572,
https://hdl.handle.net/21.15107/rcub_vinar_9458 .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Lazarov, Nenad Đ.
AU  - Spasojević, Vojislav
AU  - Milić, Mirjana M.
AU  - Kusigerski, Vladan
PY  - 2005
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2890
AB  - Distribution of CuO chains in YBa2Cu3O6+2c, with respect to different chain lengths, has been studied in terms of the two dimensional asymmetric next-nearest-neighbor Ising (ASYNNNI) model, for the case of orthorhombic-I structural phase. If p(1) stands for the fraction of CuO chains of length l (l equals to number of oxygen atoms that are linked in the chain), the results obtained show that p(!) decreases monotonically with 1, very accurately fitting to p(!) = AB(l), as at very low temperatures so at a very high temperatures as well (ranking from approximate to 300 K to 1800 K), and at all values of oxygen concentration c. Both parameters A and B were found to depend on (c, T) only through a single quantity-the average length 1, (c, T) of CuO chains in the system. The expressions for A(I-av) = A(I-av(c, T)) and B(I-av) = B(Id, (c, T)), that were derived out of extensive Monte Carlo (MC) numerical simulations on the chain probability distribution p(1) and independently obtained values of I-av were found to be very accurately fulfilled at all calculated points of (c, T) space. The particular behavior of p(!) dependance has been assigned to 1d Ising model type of oxygen atom fluctuations along cooper mediated V-2 LT 0 bonds (i.e., along b crystallographic axes). The importance of knowing the exact form of p(, for evaluation of the number of transferred electronic holes from CuO chains to superconducting CuO2 layers, has been discussed together with its possible impact on the two-plateaus shape of T-c(c) dependance. (c) 2005 Elsevier B.V. All rights reserved.
T2  - Physica. C: Superconductivity and Its Applications
T1  - A Monte Carlo study on distribution of CuO chains in YBa2Cu3O6+2c
VL  - 421
IS  - 1-4
SP  - 49
EP  - 55
DO  - 10.1016/j.physc.2005.02.009
ER  - 

@article{
author = "Matić, Vladimir M. and Lazarov, Nenad Đ. and Spasojević, Vojislav and Milić, Mirjana M. and Kusigerski, Vladan",
year = "2005",
abstract = "Distribution of CuO chains in YBa2Cu3O6+2c, with respect to different chain lengths, has been studied in terms of the two dimensional asymmetric next-nearest-neighbor Ising (ASYNNNI) model, for the case of orthorhombic-I structural phase. If p(1) stands for the fraction of CuO chains of length l (l equals to number of oxygen atoms that are linked in the chain), the results obtained show that p(!) decreases monotonically with 1, very accurately fitting to p(!) = AB(l), as at very low temperatures so at a very high temperatures as well (ranking from approximate to 300 K to 1800 K), and at all values of oxygen concentration c. Both parameters A and B were found to depend on (c, T) only through a single quantity-the average length 1, (c, T) of CuO chains in the system. The expressions for A(I-av) = A(I-av(c, T)) and B(I-av) = B(Id, (c, T)), that were derived out of extensive Monte Carlo (MC) numerical simulations on the chain probability distribution p(1) and independently obtained values of I-av were found to be very accurately fulfilled at all calculated points of (c, T) space. The particular behavior of p(!) dependance has been assigned to 1d Ising model type of oxygen atom fluctuations along cooper mediated V-2 LT 0 bonds (i.e., along b crystallographic axes). The importance of knowing the exact form of p(, for evaluation of the number of transferred electronic holes from CuO chains to superconducting CuO2 layers, has been discussed together with its possible impact on the two-plateaus shape of T-c(c) dependance. (c) 2005 Elsevier B.V. All rights reserved.",
journal = "Physica. C: Superconductivity and Its Applications",
title = "A Monte Carlo study on distribution of CuO chains in YBa2Cu3O6+2c",
volume = "421",
number = "1-4",
pages = "49-55",
doi = "10.1016/j.physc.2005.02.009"
}

Matić, V. M., Lazarov, N. Đ., Spasojević, V., Milić, M. M.,& Kusigerski, V.. (2005). A Monte Carlo study on distribution of CuO chains in YBa2Cu3O6+2c. in Physica. C: Superconductivity and Its Applications, 421(1-4), 49-55.
https://doi.org/10.1016/j.physc.2005.02.009

Matić VM, Lazarov NĐ, Spasojević V, Milić MM, Kusigerski V. A Monte Carlo study on distribution of CuO chains in YBa2Cu3O6+2c. in Physica. C: Superconductivity and Its Applications. 2005;421(1-4):49-55.
doi:10.1016/j.physc.2005.02.009 .

Matić, Vladimir M., Lazarov, Nenad Đ., Spasojević, Vojislav, Milić, Mirjana M., Kusigerski, Vladan, "A Monte Carlo study on distribution of CuO chains in YBa2Cu3O6+2c" in Physica. C: Superconductivity and Its Applications, 421, no. 1-4 (2005):49-55,
https://doi.org/10.1016/j.physc.2005.02.009 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Milić, Mirjana M.
AU  - Lazarov, Nenad Đ.
PY  - 2005
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2893
AB  - A cluster variation method (CVM) has been used to calculate the phase diagram of oxygen ordering in YBa2-Cu3O6+2c in terms of two dimensional Ising model that, besides of repulsive nearest-neighbor (NN) interaction V-1 GT 0 and two types of next-to-nearest neighbor (NNN) pair interactions V-2 LT 0 and V-3 GT 0, includes additional three-atom effective interaction V-th coupling two NNN oxygen atoms already bounded by V-2 (through Cu(l) ion) with the third O atom that is connected with one of these two by the repulsive NNN Coulomb interaction V-3 GT 0. Phase diagrams were calculated for several different sets of interaction constants V-1, V-2, V-3, and V-th together with the corresponding phase diagrams obtained for V-th = 0. The arrangement of main orthorhombic structures in (c, T) space and the nature of the phase transition curves between them is found to be in a very good agreement with those of the corresponding phase diagrams of the well-known ASYNNNI model, which had already proven itself as accurately reproducing the number of experimental findings on the structural phase diagram of YBa2Cu3O6+2c. On the other hand, unlike to the predictions of the ASYNNNI model (V-th = 0), it is shown that inclusion of three-atom interaction V-th results in significant increase of the number of isolated basal plane oxygen ions which are generally considered as not giving rise to the charge transfer process and the onset of superconductivity. The importance of obtained oxygen superstructures of low temperature oxygen ordering and its possible impact on existence of plateaus in T-c(c) dependence has been discussed. (c) 2005 Elsevier B.V. All rights reserved.
T2  - Physica. C: Superconductivity and Its Applications
T1  - Phase diagram of oxygen ordering in YBa2Cu3O6+2c. The three-atom interactions
VL  - 422
IS  - 1-2
SP  - 1
EP  - 8
DO  - 10.1016/j.physc.2005.02.010
ER  - 

@article{
author = "Matić, Vladimir M. and Milić, Mirjana M. and Lazarov, Nenad Đ.",
year = "2005",
abstract = "A cluster variation method (CVM) has been used to calculate the phase diagram of oxygen ordering in YBa2-Cu3O6+2c in terms of two dimensional Ising model that, besides of repulsive nearest-neighbor (NN) interaction V-1 GT 0 and two types of next-to-nearest neighbor (NNN) pair interactions V-2 LT 0 and V-3 GT 0, includes additional three-atom effective interaction V-th coupling two NNN oxygen atoms already bounded by V-2 (through Cu(l) ion) with the third O atom that is connected with one of these two by the repulsive NNN Coulomb interaction V-3 GT 0. Phase diagrams were calculated for several different sets of interaction constants V-1, V-2, V-3, and V-th together with the corresponding phase diagrams obtained for V-th = 0. The arrangement of main orthorhombic structures in (c, T) space and the nature of the phase transition curves between them is found to be in a very good agreement with those of the corresponding phase diagrams of the well-known ASYNNNI model, which had already proven itself as accurately reproducing the number of experimental findings on the structural phase diagram of YBa2Cu3O6+2c. On the other hand, unlike to the predictions of the ASYNNNI model (V-th = 0), it is shown that inclusion of three-atom interaction V-th results in significant increase of the number of isolated basal plane oxygen ions which are generally considered as not giving rise to the charge transfer process and the onset of superconductivity. The importance of obtained oxygen superstructures of low temperature oxygen ordering and its possible impact on existence of plateaus in T-c(c) dependence has been discussed. (c) 2005 Elsevier B.V. All rights reserved.",
journal = "Physica. C: Superconductivity and Its Applications",
title = "Phase diagram of oxygen ordering in YBa2Cu3O6+2c. The three-atom interactions",
volume = "422",
number = "1-2",
pages = "1-8",
doi = "10.1016/j.physc.2005.02.010"
}

Matić, V. M., Milić, M. M.,& Lazarov, N. Đ.. (2005). Phase diagram of oxygen ordering in YBa2Cu3O6+2c. The three-atom interactions. in Physica. C: Superconductivity and Its Applications, 422(1-2), 1-8.
https://doi.org/10.1016/j.physc.2005.02.010

Matić VM, Milić MM, Lazarov NĐ. Phase diagram of oxygen ordering in YBa2Cu3O6+2c. The three-atom interactions. in Physica. C: Superconductivity and Its Applications. 2005;422(1-2):1-8.
doi:10.1016/j.physc.2005.02.010 .

Matić, Vladimir M., Milić, Mirjana M., Lazarov, Nenad Đ., "Phase diagram of oxygen ordering in YBa2Cu3O6+2c. The three-atom interactions" in Physica. C: Superconductivity and Its Applications, 422, no. 1-2 (2005):1-8,
https://doi.org/10.1016/j.physc.2005.02.010 . .

TY  - CONF
AU  - Lazarov, Nenad
AU  - Milić, M.
AU  - Matić, Vladimir
PY  - 2004
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12904
AB  - The distribution p(l) of CuO chains in YBa2Cu3O6+2c, with respect to different chain lengths l, obeys a simple exponential-low dependence p(l)=A×Bl, where the parameters A and B are functions of oxygen concentration c and temperature T. By the use of Monte Carlo numerical simulation of the ASYNNNI model, we have found that the parameters A and B can be expressed as a functions of a single parameter: average chain length lav. This dependence is established to be valid for a large number of points in the temperature-concentration plain (for the oxygen content in the range c∈(0.39,0.50), and for the temperatures extending from τ =kBT/V1≈ 0.3 to τ ≈1.8).
C3  - SFKM 2004 : XVI National Symposium on Condensed Matter Physics : Program and Contributed Papers
T1  - Distribution Of CuO Chains In The Oxygen Deficient Planes Of YBa2Cu3O6+2c
SP  - 261
EP  - 264
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12904
ER  - 

@conference{
author = "Lazarov, Nenad and Milić, M. and Matić, Vladimir",
year = "2004",
abstract = "The distribution p(l) of CuO chains in YBa2Cu3O6+2c, with respect to different chain lengths l, obeys a simple exponential-low dependence p(l)=A×Bl, where the parameters A and B are functions of oxygen concentration c and temperature T. By the use of Monte Carlo numerical simulation of the ASYNNNI model, we have found that the parameters A and B can be expressed as a functions of a single parameter: average chain length lav. This dependence is established to be valid for a large number of points in the temperature-concentration plain (for the oxygen content in the range c∈(0.39,0.50), and for the temperatures extending from τ =kBT/V1≈ 0.3 to τ ≈1.8).",
journal = "SFKM 2004 : XVI National Symposium on Condensed Matter Physics : Program and Contributed Papers",
title = "Distribution Of CuO Chains In The Oxygen Deficient Planes Of YBa2Cu3O6+2c",
pages = "261-264",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12904"
}

Lazarov, N., Milić, M.,& Matić, V.. (2004). Distribution Of CuO Chains In The Oxygen Deficient Planes Of YBa2Cu3O6+2c. in SFKM 2004 : XVI National Symposium on Condensed Matter Physics : Program and Contributed Papers, 261-264.
https://hdl.handle.net/21.15107/rcub_vinar_12904

Lazarov N, Milić M, Matić V. Distribution Of CuO Chains In The Oxygen Deficient Planes Of YBa2Cu3O6+2c. in SFKM 2004 : XVI National Symposium on Condensed Matter Physics : Program and Contributed Papers. 2004;:261-264.
https://hdl.handle.net/21.15107/rcub_vinar_12904 .

Lazarov, Nenad, Milić, M., Matić, Vladimir, "Distribution Of CuO Chains In The Oxygen Deficient Planes Of YBa2Cu3O6+2c" in SFKM 2004 : XVI National Symposium on Condensed Matter Physics : Program and Contributed Papers (2004):261-264,
https://hdl.handle.net/21.15107/rcub_vinar_12904 .

TY  - JOUR
AU  - Lazarov, Nenad Đ.
AU  - Spasojević, Vojislav
AU  - Kusigerski, Vladan
AU  - Matić, Vladimir M.
AU  - Milić, Mirjana M.
PY  - 2004
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6454
AB  - Magnetic properties of the dinuclear cobalt complex originate from the magnetically isolated asymmetric dimers where each Co(II) ion within the dimer is situated in the differently distorted octahedral ligand field. Calculated values of magnetic susceptibility, obtained by use of the anisotropic Heisenberg-asymmetric dimer model, are found to be in excellent agreement with experimental chi(T) data over a wide range of temperature (4-295 K). Values of fitted parameters, the exchange integral J and both g-factors of the dimer, are in a very good agreement with the literature data. (C) 2004 Elsevier B.V. All rights reserved.
T2  - Journal of Magnetism and Magnetic Materials
T1  - Magnetic susceptibility calculation of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2) center dot 3H(2)O
VL  - 272
SP  - 1065
EP  - 1066
DO  - 10.1016/j.jmmm.2003.12.010
ER  - 

@article{
author = "Lazarov, Nenad Đ. and Spasojević, Vojislav and Kusigerski, Vladan and Matić, Vladimir M. and Milić, Mirjana M.",
year = "2004",
abstract = "Magnetic properties of the dinuclear cobalt complex originate from the magnetically isolated asymmetric dimers where each Co(II) ion within the dimer is situated in the differently distorted octahedral ligand field. Calculated values of magnetic susceptibility, obtained by use of the anisotropic Heisenberg-asymmetric dimer model, are found to be in excellent agreement with experimental chi(T) data over a wide range of temperature (4-295 K). Values of fitted parameters, the exchange integral J and both g-factors of the dimer, are in a very good agreement with the literature data. (C) 2004 Elsevier B.V. All rights reserved.",
journal = "Journal of Magnetism and Magnetic Materials",
title = "Magnetic susceptibility calculation of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2) center dot 3H(2)O",
volume = "272",
pages = "1065-1066",
doi = "10.1016/j.jmmm.2003.12.010"
}

Lazarov, N. Đ., Spasojević, V., Kusigerski, V., Matić, V. M.,& Milić, M. M.. (2004). Magnetic susceptibility calculation of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2) center dot 3H(2)O. in Journal of Magnetism and Magnetic Materials, 272, 1065-1066.
https://doi.org/10.1016/j.jmmm.2003.12.010

Lazarov NĐ, Spasojević V, Kusigerski V, Matić VM, Milić MM. Magnetic susceptibility calculation of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2) center dot 3H(2)O. in Journal of Magnetism and Magnetic Materials. 2004;272:1065-1066.
doi:10.1016/j.jmmm.2003.12.010 .

Lazarov, Nenad Đ., Spasojević, Vojislav, Kusigerski, Vladan, Matić, Vladimir M., Milić, Mirjana M., "Magnetic susceptibility calculation of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2) center dot 3H(2)O" in Journal of Magnetism and Magnetic Materials, 272 (2004):1065-1066,
https://doi.org/10.1016/j.jmmm.2003.12.010 . .

TY  - JOUR
AU  - Kusigerski, Vladan
AU  - Spasojević, Vojislav
AU  - Lazarov, Nenad Đ.
AU  - Markovic, DS
AU  - Matić, Vladimir M.
AU  - Sovilj, Sofija P.
AU  - Guillot, M
PY  - 2003
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2627
AB  - Magnetic properties of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2).3H(2)O have been studied from the magnetization data obtained in the high magnetic field-low temperature experiment (B less than or equal to 20 T, T = 4.2 K). An excellent agreement between experimental and calculated data was achieved within the framework of the isolated Ising Co(H) pairs in the ground state, where each cobalt ion from the pair was situated in a differently distorted octahedral environment (asymmetric dimer). The obtained values for g-factors, g(a) = (4.5 +/- 0.1) and g(b) = (3.3 +/- 0.1), and for the intracluster exchange integral J = (-16.0 +/- 0.5) K confirm both the previous results on the crystal structure of the complex under consideration and the assumption on the strong antiferromagnetic coupling between cobalt ions realized by the superexchange interaction over the asymmetric oxalato bridge. (C) 2003 Published by Elsevier Science Ltd.
T2  - Solid State Communications
T1  - High magnetic fields study of asymmetric Co(II) dimer in octahedral ligand environment
VL  - 126
IS  - 6
SP  - 319
EP  - 322
DO  - 10.1016/S0038-1098(03)00163-7
ER  - 

@article{
author = "Kusigerski, Vladan and Spasojević, Vojislav and Lazarov, Nenad Đ. and Markovic, DS and Matić, Vladimir M. and Sovilj, Sofija P. and Guillot, M",
year = "2003",
abstract = "Magnetic properties of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2).3H(2)O have been studied from the magnetization data obtained in the high magnetic field-low temperature experiment (B less than or equal to 20 T, T = 4.2 K). An excellent agreement between experimental and calculated data was achieved within the framework of the isolated Ising Co(H) pairs in the ground state, where each cobalt ion from the pair was situated in a differently distorted octahedral environment (asymmetric dimer). The obtained values for g-factors, g(a) = (4.5 +/- 0.1) and g(b) = (3.3 +/- 0.1), and for the intracluster exchange integral J = (-16.0 +/- 0.5) K confirm both the previous results on the crystal structure of the complex under consideration and the assumption on the strong antiferromagnetic coupling between cobalt ions realized by the superexchange interaction over the asymmetric oxalato bridge. (C) 2003 Published by Elsevier Science Ltd.",
journal = "Solid State Communications",
title = "High magnetic fields study of asymmetric Co(II) dimer in octahedral ligand environment",
volume = "126",
number = "6",
pages = "319-322",
doi = "10.1016/S0038-1098(03)00163-7"
}

Kusigerski, V., Spasojević, V., Lazarov, N. Đ., Markovic, D., Matić, V. M., Sovilj, S. P.,& Guillot, M.. (2003). High magnetic fields study of asymmetric Co(II) dimer in octahedral ligand environment. in Solid State Communications, 126(6), 319-322.
https://doi.org/10.1016/S0038-1098(03)00163-7

Kusigerski V, Spasojević V, Lazarov NĐ, Markovic D, Matić VM, Sovilj SP, Guillot M. High magnetic fields study of asymmetric Co(II) dimer in octahedral ligand environment. in Solid State Communications. 2003;126(6):319-322.
doi:10.1016/S0038-1098(03)00163-7 .

Kusigerski, Vladan, Spasojević, Vojislav, Lazarov, Nenad Đ., Markovic, DS, Matić, Vladimir M., Sovilj, Sofija P., Guillot, M, "High magnetic fields study of asymmetric Co(II) dimer in octahedral ligand environment" in Solid State Communications, 126, no. 6 (2003):319-322,
https://doi.org/10.1016/S0038-1098(03)00163-7 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Milić, Mirjana M.
AU  - Tornau, EE
AU  - Lapinskas, S
AU  - Lazarov, Nenad Đ.
PY  - 2001
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2409
AB  - Fluctuations in tetragonal phase of YBa2Cu3O6+2c compound are analyzed in terms of the two-dimensional asymmetric next-nearest-neighbor Ising (ASYNNNI) model. For several sets of interaction constants between oxygen atoms, VI GT 0. V-2 LT 0 and V-3 GT 0, we calculated equidistant mu (c, T) = constant curves to show that largest fluctuations of oxygen concentration in tetragonal phase occur for chemical potential mu approximate to mu (g1), where mu (g1) = -8V(1) - 4V(3). We argue that this is a general property of the ASYNNNI model: it holds for all temperatures and different values of interaction constants. Analyzing the experimental results on isothermal susceptibility, chi = sigmac/sigma mu for six different temperatures ranging from 673 to 923 K, we found that the top of chi occurs for approximately the same value of oxygen chemical potential in gas phase which corresponds to mu (gi) of the ASYNNNI model. By comparison with experiment, we obtained the relation, 4 \V-2\ - epsilon = 82 mRy, where epsilon is the on-site energy of the basal plane oxygen atoms. (C) 2001 Elsevier Science B.V. All rights reserved.
T2  - Physica. C: Superconductivity and Its Applications
T1  - Isothermal susceptibility in tetragonal phase of YBa2Cu3O6+2c
VL  - 349
IS  - 3-4
SP  - 246
EP  - 250
DO  - 10.1016/S0921-4534(00)01543-4
ER  - 

@article{
author = "Matić, Vladimir M. and Milić, Mirjana M. and Tornau, EE and Lapinskas, S and Lazarov, Nenad Đ.",
year = "2001",
abstract = "Fluctuations in tetragonal phase of YBa2Cu3O6+2c compound are analyzed in terms of the two-dimensional asymmetric next-nearest-neighbor Ising (ASYNNNI) model. For several sets of interaction constants between oxygen atoms, VI GT 0. V-2 LT 0 and V-3 GT 0, we calculated equidistant mu (c, T) = constant curves to show that largest fluctuations of oxygen concentration in tetragonal phase occur for chemical potential mu approximate to mu (g1), where mu (g1) = -8V(1) - 4V(3). We argue that this is a general property of the ASYNNNI model: it holds for all temperatures and different values of interaction constants. Analyzing the experimental results on isothermal susceptibility, chi = sigmac/sigma mu for six different temperatures ranging from 673 to 923 K, we found that the top of chi occurs for approximately the same value of oxygen chemical potential in gas phase which corresponds to mu (gi) of the ASYNNNI model. By comparison with experiment, we obtained the relation, 4 \V-2\ - epsilon = 82 mRy, where epsilon is the on-site energy of the basal plane oxygen atoms. (C) 2001 Elsevier Science B.V. All rights reserved.",
journal = "Physica. C: Superconductivity and Its Applications",
title = "Isothermal susceptibility in tetragonal phase of YBa2Cu3O6+2c",
volume = "349",
number = "3-4",
pages = "246-250",
doi = "10.1016/S0921-4534(00)01543-4"
}

Matić, V. M., Milić, M. M., Tornau, E., Lapinskas, S.,& Lazarov, N. Đ.. (2001). Isothermal susceptibility in tetragonal phase of YBa2Cu3O6+2c. in Physica. C: Superconductivity and Its Applications, 349(3-4), 246-250.
https://doi.org/10.1016/S0921-4534(00)01543-4

Matić VM, Milić MM, Tornau E, Lapinskas S, Lazarov NĐ. Isothermal susceptibility in tetragonal phase of YBa2Cu3O6+2c. in Physica. C: Superconductivity and Its Applications. 2001;349(3-4):246-250.
doi:10.1016/S0921-4534(00)01543-4 .

Matić, Vladimir M., Milić, Mirjana M., Tornau, EE, Lapinskas, S, Lazarov, Nenad Đ., "Isothermal susceptibility in tetragonal phase of YBa2Cu3O6+2c" in Physica. C: Superconductivity and Its Applications, 349, no. 3-4 (2001):246-250,
https://doi.org/10.1016/S0921-4534(00)01543-4 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Wille, LT
AU  - Lazarov, Nenad Đ.
AU  - Milić, Mirjana M.
PY  - 2001
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2487
AB  - We Study the low-temperature thermodynamical and statistical properties of the ASYNNNI model, used to describe oxygen ordering in YBa2Cu3O6+2c. Analyzing the excited states we show that this model undergoes a second order phase transition at absolute zero temperature, From the divergence of the relative energy fluctuations, in the limit T -- GT 0, we deduce that for T approximate to 0 the deviation of the chemical potential it from its ground state value is linearly related to the partial derivative of the fraction of threefold coordinated Cu(1) ions it with respect to oxygen concentlation c. We use the cluster variation method (CVM) to determine the numerical value of the coefficient of this, relation and find that it is equal to - 1/2, independently of the values of the interaction parameters. This establishes a full equivalence between the ASYNNNI model and the one-dimensional Ising model, where the role of the nearest-neighbor interaction of the latter is played by the V-2 interaction in the former. We comment on the general applicability of low levels of the CVM approximation to systems equivalent to the one-dimensional Ising model.
T2  - Materials Transactions. JIM / Japan Institute of Metals
T1  - A cluster variation method approach to the problem of low-temperature statistics of a class of Ising models
VL  - 42
IS  - 11
SP  - 2157
EP  - 2164
DO  - 10.2320/matertrans.42.2157
ER  - 

@article{
author = "Matić, Vladimir M. and Wille, LT and Lazarov, Nenad Đ. and Milić, Mirjana M.",
year = "2001",
abstract = "We Study the low-temperature thermodynamical and statistical properties of the ASYNNNI model, used to describe oxygen ordering in YBa2Cu3O6+2c. Analyzing the excited states we show that this model undergoes a second order phase transition at absolute zero temperature, From the divergence of the relative energy fluctuations, in the limit T -- GT 0, we deduce that for T approximate to 0 the deviation of the chemical potential it from its ground state value is linearly related to the partial derivative of the fraction of threefold coordinated Cu(1) ions it with respect to oxygen concentlation c. We use the cluster variation method (CVM) to determine the numerical value of the coefficient of this, relation and find that it is equal to - 1/2, independently of the values of the interaction parameters. This establishes a full equivalence between the ASYNNNI model and the one-dimensional Ising model, where the role of the nearest-neighbor interaction of the latter is played by the V-2 interaction in the former. We comment on the general applicability of low levels of the CVM approximation to systems equivalent to the one-dimensional Ising model.",
journal = "Materials Transactions. JIM / Japan Institute of Metals",
title = "A cluster variation method approach to the problem of low-temperature statistics of a class of Ising models",
volume = "42",
number = "11",
pages = "2157-2164",
doi = "10.2320/matertrans.42.2157"
}

Matić, V. M., Wille, L., Lazarov, N. Đ.,& Milić, M. M.. (2001). A cluster variation method approach to the problem of low-temperature statistics of a class of Ising models. in Materials Transactions. JIM / Japan Institute of Metals, 42(11), 2157-2164.
https://doi.org/10.2320/matertrans.42.2157

Matić VM, Wille L, Lazarov NĐ, Milić MM. A cluster variation method approach to the problem of low-temperature statistics of a class of Ising models. in Materials Transactions. JIM / Japan Institute of Metals. 2001;42(11):2157-2164.
doi:10.2320/matertrans.42.2157 .

Matić, Vladimir M., Wille, LT, Lazarov, Nenad Đ., Milić, Mirjana M., "A cluster variation method approach to the problem of low-temperature statistics of a class of Ising models" in Materials Transactions. JIM / Japan Institute of Metals, 42, no. 11 (2001):2157-2164,
https://doi.org/10.2320/matertrans.42.2157 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Milić, Mirjana M.
AU  - Lazarov, Nenad Đ.
PY  - 2000
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2379
AB  - We proposed a two-dimensional Ising model for oxygen ordering in YBa2Cu3Ox material in which an effective O-O interaction energy with Cull) ion in between, besides the occupation of the two oxygen sites, also depends on occupancy of the surrounding oxygen sites. We have shown that the Hamiltonian of the model reduces to that of the anisotropic next-nearest-neighbor Ising (ASYNNNI) model with additional term, for three-atom interaction (characterized by the parameter omega). We have shown that, for omega GT /V-2//4 (where V-2 LT 0 denotes copper mediated O-O interaction of the ASYNNNI model), the model includes all three major structural phases, tetragonal, OI, and OII, as ground states at x = 0, x = 6.5, and x = 7.0, respectively, while at off-stoichiometry 6.5 LT x LT 7, the model stabilizes the so-called fragmented-chain structure of Zaanen et al. [J. Zaanen, A.T. Paxton, O. Jepsen, O.K. Anderson, Phys. Rev. Lett. 60 (1988) 2685]. We calculated the fractions of 2-fold (n(2)), 3-fold (n(3)) and 4-fold (n(4)) coordinated Cu(1) ions as a function of oxygen content x at constant low temperatures (proportional to 300 K) and obtained characteristic plateaus in n(2)(x) and n(4)(x), while n(3)(x) is very large (proportional to 0.36) for x = 6.75. We discussed the impact of the fragmented chain statistics on charge transfer process from Cu(1)-O(1) chains to superconducting CuO2 sheets and its relevance for occurrence of 60 and 90 K plateaus in T-c versus x dependence. (C) 2000 Elsevier Science B.V. All rights reserved.
T2  - Physica. C: Superconductivity and Its Applications
T1  - A model of oxygen ordering in YBa2Cu3Ox. Fragmented-chain structure at 6.5 LT x LT 7
VL  - 339
IS  - 1
SP  - 27
EP  - 36
DO  - 10.1016/S0921-4534(00)00328-2
ER  - 

@article{
author = "Matić, Vladimir M. and Milić, Mirjana M. and Lazarov, Nenad Đ.",
year = "2000",
abstract = "We proposed a two-dimensional Ising model for oxygen ordering in YBa2Cu3Ox material in which an effective O-O interaction energy with Cull) ion in between, besides the occupation of the two oxygen sites, also depends on occupancy of the surrounding oxygen sites. We have shown that the Hamiltonian of the model reduces to that of the anisotropic next-nearest-neighbor Ising (ASYNNNI) model with additional term, for three-atom interaction (characterized by the parameter omega). We have shown that, for omega GT /V-2//4 (where V-2 LT 0 denotes copper mediated O-O interaction of the ASYNNNI model), the model includes all three major structural phases, tetragonal, OI, and OII, as ground states at x = 0, x = 6.5, and x = 7.0, respectively, while at off-stoichiometry 6.5 LT x LT 7, the model stabilizes the so-called fragmented-chain structure of Zaanen et al. [J. Zaanen, A.T. Paxton, O. Jepsen, O.K. Anderson, Phys. Rev. Lett. 60 (1988) 2685]. We calculated the fractions of 2-fold (n(2)), 3-fold (n(3)) and 4-fold (n(4)) coordinated Cu(1) ions as a function of oxygen content x at constant low temperatures (proportional to 300 K) and obtained characteristic plateaus in n(2)(x) and n(4)(x), while n(3)(x) is very large (proportional to 0.36) for x = 6.75. We discussed the impact of the fragmented chain statistics on charge transfer process from Cu(1)-O(1) chains to superconducting CuO2 sheets and its relevance for occurrence of 60 and 90 K plateaus in T-c versus x dependence. (C) 2000 Elsevier Science B.V. All rights reserved.",
journal = "Physica. C: Superconductivity and Its Applications",
title = "A model of oxygen ordering in YBa2Cu3Ox. Fragmented-chain structure at 6.5 LT x LT 7",
volume = "339",
number = "1",
pages = "27-36",
doi = "10.1016/S0921-4534(00)00328-2"
}

Matić, V. M., Milić, M. M.,& Lazarov, N. Đ.. (2000). A model of oxygen ordering in YBa2Cu3Ox. Fragmented-chain structure at 6.5 LT x LT 7. in Physica. C: Superconductivity and Its Applications, 339(1), 27-36.
https://doi.org/10.1016/S0921-4534(00)00328-2

Matić VM, Milić MM, Lazarov NĐ. A model of oxygen ordering in YBa2Cu3Ox. Fragmented-chain structure at 6.5 LT x LT 7. in Physica. C: Superconductivity and Its Applications. 2000;339(1):27-36.
doi:10.1016/S0921-4534(00)00328-2 .

Matić, Vladimir M., Milić, Mirjana M., Lazarov, Nenad Đ., "A model of oxygen ordering in YBa2Cu3Ox. Fragmented-chain structure at 6.5 LT x LT 7" in Physica. C: Superconductivity and Its Applications, 339, no. 1 (2000):27-36,
https://doi.org/10.1016/S0921-4534(00)00328-2 . .

TY  - JOUR
AU  - Matić, Vladimir M.
AU  - Milošević, Sava
PY  - 1999
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2219
AB  - We have analyzed relationship between two parallel approaches to the cluster variation method (CVM) as a theoretical tool for studying statistical properties of binary systems. The first approach to the method uses the multisite correlation functions as variational variables, while the other approach is the one that uses the cluster effective fields as variational variables. Using the Ising model description of physical systems studied, we have shown that the two approaches should produce identical final results, although they deal with quite different systems of nonlinear equations (which, in particular cases under study, must be solved numerically for a given temperature and chemical potential). To achieve identical final results, we show that it is necessary to introduce cluster fields for those clusters which appear to be subclusters of at least two different members of the Kikuchi cluster family. In addition, we demonstrate that variational variables of the two approaches generate two sets of cluster probabilities, whose intersection contains solution of the CVM approximation which corresponds to the thermodynamic equilibrium state. We also analyze the existence of the so-called consistency relations in both approaches to the CVM method, and, finally, we discuss the problem of convergency of numerical procedures that are used to analyze the low-temperature states of the model systems under study. (C) 1999 Elsevier Science B.V. All rights reserved.
T2  - Physica A: Statistical Mechanics and Its Applications
T1  - Equivalence of two parallel approaches to the cluster variation method: the multisite correlation functions method and the cluster effective fields method
VL  - 262
IS  - 1-2
SP  - 215
EP  - 231
DO  - 10.1016/S0378-4371(98)00406-3
ER  - 

@article{
author = "Matić, Vladimir M. and Milošević, Sava",
year = "1999",
abstract = "We have analyzed relationship between two parallel approaches to the cluster variation method (CVM) as a theoretical tool for studying statistical properties of binary systems. The first approach to the method uses the multisite correlation functions as variational variables, while the other approach is the one that uses the cluster effective fields as variational variables. Using the Ising model description of physical systems studied, we have shown that the two approaches should produce identical final results, although they deal with quite different systems of nonlinear equations (which, in particular cases under study, must be solved numerically for a given temperature and chemical potential). To achieve identical final results, we show that it is necessary to introduce cluster fields for those clusters which appear to be subclusters of at least two different members of the Kikuchi cluster family. In addition, we demonstrate that variational variables of the two approaches generate two sets of cluster probabilities, whose intersection contains solution of the CVM approximation which corresponds to the thermodynamic equilibrium state. We also analyze the existence of the so-called consistency relations in both approaches to the CVM method, and, finally, we discuss the problem of convergency of numerical procedures that are used to analyze the low-temperature states of the model systems under study. (C) 1999 Elsevier Science B.V. All rights reserved.",
journal = "Physica A: Statistical Mechanics and Its Applications",
title = "Equivalence of two parallel approaches to the cluster variation method: the multisite correlation functions method and the cluster effective fields method",
volume = "262",
number = "1-2",
pages = "215-231",
doi = "10.1016/S0378-4371(98)00406-3"
}

Matić, V. M.,& Milošević, S.. (1999). Equivalence of two parallel approaches to the cluster variation method: the multisite correlation functions method and the cluster effective fields method. in Physica A: Statistical Mechanics and Its Applications, 262(1-2), 215-231.
https://doi.org/10.1016/S0378-4371(98)00406-3

Matić VM, Milošević S. Equivalence of two parallel approaches to the cluster variation method: the multisite correlation functions method and the cluster effective fields method. in Physica A: Statistical Mechanics and Its Applications. 1999;262(1-2):215-231.
doi:10.1016/S0378-4371(98)00406-3 .

Matić, Vladimir M., Milošević, Sava, "Equivalence of two parallel approaches to the cluster variation method: the multisite correlation functions method and the cluster effective fields method" in Physica A: Statistical Mechanics and Its Applications, 262, no. 1-2 (1999):215-231,
https://doi.org/10.1016/S0378-4371(98)00406-3 . .

TY  - JOUR
AU  - Matić, Vladimir M.
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6232
AB  - We present an implementation of the cluster variation method (CVM), applied to the Ising model, for computational characterization of order-disorder processes in binary systems. We show how the Newton-Raphson iteration scheme (NRIS) is used for numerical solving of system of nonlinear equations, obtained from the condition of the free energy minimum within the framework of the CVM approximation. An emphasis is made on the problem of the starting iteration point (NRIS being very sensitive to the choise of this point), for obtaining the low-temperature ordered phases. It was shown that an infinitesimally small breaking of symmetry of the high-temperature disordered phases supresses finding solutions which correspond to the metastable phases (saddle points) by NRIS (below the critical temperature T-c). This kind of problem is illustrated by an example of oxygen ordering in basal planes of YBa2Cu3O6+x system, modeled by the two-dimensional asymetric next-nearest neighbor Ising (ASYNNNI) model. Copyright (C) 1998 Elsevier Science B.V.
T2  - Computational Materials Science
T1  - Computational treatment of order-disorder processes by use of the cluster variation method
VL  - 10
IS  - 1-4
SP  - 421
EP  - 426
DO  - 10.1016/S0927-0256(97)00112-2
ER  - 

@article{
author = "Matić, Vladimir M.",
year = "1998",
abstract = "We present an implementation of the cluster variation method (CVM), applied to the Ising model, for computational characterization of order-disorder processes in binary systems. We show how the Newton-Raphson iteration scheme (NRIS) is used for numerical solving of system of nonlinear equations, obtained from the condition of the free energy minimum within the framework of the CVM approximation. An emphasis is made on the problem of the starting iteration point (NRIS being very sensitive to the choise of this point), for obtaining the low-temperature ordered phases. It was shown that an infinitesimally small breaking of symmetry of the high-temperature disordered phases supresses finding solutions which correspond to the metastable phases (saddle points) by NRIS (below the critical temperature T-c). This kind of problem is illustrated by an example of oxygen ordering in basal planes of YBa2Cu3O6+x system, modeled by the two-dimensional asymetric next-nearest neighbor Ising (ASYNNNI) model. Copyright (C) 1998 Elsevier Science B.V.",
journal = "Computational Materials Science",
title = "Computational treatment of order-disorder processes by use of the cluster variation method",
volume = "10",
number = "1-4",
pages = "421-426",
doi = "10.1016/S0927-0256(97)00112-2"
}

Matić, V. M.. (1998). Computational treatment of order-disorder processes by use of the cluster variation method. in Computational Materials Science, 10(1-4), 421-426.
https://doi.org/10.1016/S0927-0256(97)00112-2

Matić VM. Computational treatment of order-disorder processes by use of the cluster variation method. in Computational Materials Science. 1998;10(1-4):421-426.
doi:10.1016/S0927-0256(97)00112-2 .

Matić, Vladimir M., "Computational treatment of order-disorder processes by use of the cluster variation method" in Computational Materials Science, 10, no. 1-4 (1998):421-426,
https://doi.org/10.1016/S0927-0256(97)00112-2 . .