TY  - JOUR
AU  - Koltunowicz, T. N.
AU  - Zukowski, P.
AU  - Milosavljević, Momir
AU  - Saad, A. M.
AU  - Kasiuk, J. V.
AU  - Fedotova, J. A.
AU  - Kalinin, Yu E.
AU  - Sitnikov, A. V.
AU  - Fedotov, A. K.
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5788
AB  - The present paper investigates dependencies of DC/AC conductances on metallic-to-dielectric phase ratio x, temperature T and frequency f in granular nanocomposite films containing FeCoZr nanoparticles embedded into oxygen-free CaF2 matrix. The specific admittance/conductance dependences on x/T/f for the studied films around the percolation configuration was found to be in agreement with their phase structure which was strongly dependent on the composition of gas atmosphere at deposition. The character of temperature/frequency dependences of AC/DC conductance indicates the predominance of electron tunneling (hopping) over the barriers between metallic nanoparticles in carrier transport. (C) 2012 Elsevier B. V. All rights reserved.
T2  - Journal of Alloys and Compounds
T1  - AC/DC conductance in granular nanocomposite films (Fe45Co45Zr10)(x)(CaF2)(100-x)
VL  - 586
SP  - S353
EP  - S356
DO  - 10.1016/j.jallcom.2012.09.121
ER  - 

@article{
author = "Koltunowicz, T. N. and Zukowski, P. and Milosavljević, Momir and Saad, A. M. and Kasiuk, J. V. and Fedotova, J. A. and Kalinin, Yu E. and Sitnikov, A. V. and Fedotov, A. K.",
year = "2014",
abstract = "The present paper investigates dependencies of DC/AC conductances on metallic-to-dielectric phase ratio x, temperature T and frequency f in granular nanocomposite films containing FeCoZr nanoparticles embedded into oxygen-free CaF2 matrix. The specific admittance/conductance dependences on x/T/f for the studied films around the percolation configuration was found to be in agreement with their phase structure which was strongly dependent on the composition of gas atmosphere at deposition. The character of temperature/frequency dependences of AC/DC conductance indicates the predominance of electron tunneling (hopping) over the barriers between metallic nanoparticles in carrier transport. (C) 2012 Elsevier B. V. All rights reserved.",
journal = "Journal of Alloys and Compounds",
title = "AC/DC conductance in granular nanocomposite films (Fe45Co45Zr10)(x)(CaF2)(100-x)",
volume = "586",
pages = "S353-S356",
doi = "10.1016/j.jallcom.2012.09.121"
}

Koltunowicz, T. N., Zukowski, P., Milosavljević, M., Saad, A. M., Kasiuk, J. V., Fedotova, J. A., Kalinin, Y. E., Sitnikov, A. V.,& Fedotov, A. K.. (2014). AC/DC conductance in granular nanocomposite films (Fe45Co45Zr10)(x)(CaF2)(100-x). in Journal of Alloys and Compounds, 586, S353-S356.
https://doi.org/10.1016/j.jallcom.2012.09.121

Koltunowicz TN, Zukowski P, Milosavljević M, Saad AM, Kasiuk JV, Fedotova JA, Kalinin YE, Sitnikov AV, Fedotov AK. AC/DC conductance in granular nanocomposite films (Fe45Co45Zr10)(x)(CaF2)(100-x). in Journal of Alloys and Compounds. 2014;586:S353-S356.
doi:10.1016/j.jallcom.2012.09.121 .

Koltunowicz, T. N., Zukowski, P., Milosavljević, Momir, Saad, A. M., Kasiuk, J. V., Fedotova, J. A., Kalinin, Yu E., Sitnikov, A. V., Fedotov, A. K., "AC/DC conductance in granular nanocomposite films (Fe45Co45Zr10)(x)(CaF2)(100-x)" in Journal of Alloys and Compounds, 586 (2014):S353-S356,
https://doi.org/10.1016/j.jallcom.2012.09.121 . .

TY  - JOUR
AU  - Koltunowicz, T. N.
AU  - Zhukowski, P.
AU  - Bondariev, V.
AU  - Saad, A.
AU  - Fedotova, J. A.
AU  - Fedotov, A. K.
AU  - Milosavljević, Momir
AU  - Kasiuk, J. V.
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7040
AB  - The paper presents frequency f and temperature T-p dependences of phase shift angle Theta, admittance sigma and capacitance C-p for the as-deposited and annealed (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion-beam sputtering of a compound target in a mixed argon-oxygen gas atmosphere in vacuum chamber. The studied films presented metallic FeCoZr cores covered with FeCo-based oxide shells embedded into oxygen-free dielectric matrix (fluorite). It was found for the metallic phase content within the range of 52.2 at.% LT = x LT = 84.3 at.% in low-f region that Theta values were negative, while in the high-f region we observed the Theta LT 0 degrees. It was obtained that the f-dependences of capacitance module displayed minimum at the corresponding frequency when the Theta(f) crossed its zero line Theta = 0 degrees. It was also observed that the sigma(T-p) dependence displayed the occurrence of two minima that were related to the values of Theta(1) = 90 degrees (the first minimum) and of Theta(2)= -90 degrees (the second one). Some possible reasons of such behavior of (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films are discussed. (C) 2013 Elsevier B.V. All rights reserved.
T2  - Journal of Alloys and Compounds
T1  - Enhancement of negative capacitance effect in (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion beam sputtering in argon and oxygen atmosphere
VL  - 615
SP  - S361
EP  - S365
DO  - 10.1016/j.jallcom.2013.12.125
ER  - 

@article{
author = "Koltunowicz, T. N. and Zhukowski, P. and Bondariev, V. and Saad, A. and Fedotova, J. A. and Fedotov, A. K. and Milosavljević, Momir and Kasiuk, J. V.",
year = "2014",
abstract = "The paper presents frequency f and temperature T-p dependences of phase shift angle Theta, admittance sigma and capacitance C-p for the as-deposited and annealed (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion-beam sputtering of a compound target in a mixed argon-oxygen gas atmosphere in vacuum chamber. The studied films presented metallic FeCoZr cores covered with FeCo-based oxide shells embedded into oxygen-free dielectric matrix (fluorite). It was found for the metallic phase content within the range of 52.2 at.% LT = x LT = 84.3 at.% in low-f region that Theta values were negative, while in the high-f region we observed the Theta LT 0 degrees. It was obtained that the f-dependences of capacitance module displayed minimum at the corresponding frequency when the Theta(f) crossed its zero line Theta = 0 degrees. It was also observed that the sigma(T-p) dependence displayed the occurrence of two minima that were related to the values of Theta(1) = 90 degrees (the first minimum) and of Theta(2)= -90 degrees (the second one). Some possible reasons of such behavior of (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films are discussed. (C) 2013 Elsevier B.V. All rights reserved.",
journal = "Journal of Alloys and Compounds",
title = "Enhancement of negative capacitance effect in (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion beam sputtering in argon and oxygen atmosphere",
volume = "615",
pages = "S361-S365",
doi = "10.1016/j.jallcom.2013.12.125"
}

Koltunowicz, T. N., Zhukowski, P., Bondariev, V., Saad, A., Fedotova, J. A., Fedotov, A. K., Milosavljević, M.,& Kasiuk, J. V.. (2014). Enhancement of negative capacitance effect in (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion beam sputtering in argon and oxygen atmosphere. in Journal of Alloys and Compounds, 615, S361-S365.
https://doi.org/10.1016/j.jallcom.2013.12.125

Koltunowicz TN, Zhukowski P, Bondariev V, Saad A, Fedotova JA, Fedotov AK, Milosavljević M, Kasiuk JV. Enhancement of negative capacitance effect in (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion beam sputtering in argon and oxygen atmosphere. in Journal of Alloys and Compounds. 2014;615:S361-S365.
doi:10.1016/j.jallcom.2013.12.125 .

Koltunowicz, T. N., Zhukowski, P., Bondariev, V., Saad, A., Fedotova, J. A., Fedotov, A. K., Milosavljević, Momir, Kasiuk, J. V., "Enhancement of negative capacitance effect in (CoFeZr)(x)(CaF2)((100-x)) nanocomposite films deposited by ion beam sputtering in argon and oxygen atmosphere" in Journal of Alloys and Compounds, 615 (2014):S361-S365,
https://doi.org/10.1016/j.jallcom.2013.12.125 . .

TY  - JOUR
AU  - Kasiuk, J. V.
AU  - Fedotova, J. A.
AU  - Przewoznik, J.
AU  - Zukrowski, J.
AU  - Sikora, M.
AU  - Kapusta, Cz
AU  - Grce, Ana
AU  - Milosavljević, Momir
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/77
AB  - The relation between nanoscale structure, local atomic order and magnetic properties of (FeCoZr)(x)(CaF2)(100-x) (29 LT = x LT = 73 at. %) granular films is studied as a function of metal/insulator fraction ratio. The films of a thickness of 1-6 mu m were deposited on Al-foils and glass-ceramic substrates, by ion sputtering of targets of different metal/insulator contents. Structural characterization with X-ray and electron diffraction as well as transmission electron microscopy revealed that the films are composed of isolated nanocrystalline bcc alpha-FeCo(Zr) alloy and insulating fcc CaF2 matrix. They grow in a columnar structure, where elongated metallic nanograins are arranged on top of each other within the columns almost normal to the substrate surface. Mossbauer spectroscopy and magnetometry results indicate that their easy magnetization axes are oriented at an angle of 65 degrees-74 degrees to the surface in films with x between 46 and 74, above the electrical percolation threshold, which is attributed to the growth-induced shape anisotropy. Interatomic distances characteristic for metallic state of alpha-FeCo(Zr) nanograins were revealed by X-ray Absorption Spectroscopy. The results show a lack of surface oxidation of the alloy nanograins, so the growth-induced orientation of nanograins in the films cannot be attributed to this effect. The study is among the first to report a growth-induced non-planar magnetic anisotropy in metal/insulator granular films above the percolation threshold and to reveal the origin of it. (C) 2014 AIP Publishing LLC.
T2  - Journal of Applied Physics
T1  - Growth-induced non-planar magnetic anisotropy in FeCoZr-CaF2 nanogranular films: Structural and magnetic characterization
VL  - 116
IS  - 4
DO  - 10.1063/1.4891016
ER  - 

@article{
author = "Kasiuk, J. V. and Fedotova, J. A. and Przewoznik, J. and Zukrowski, J. and Sikora, M. and Kapusta, Cz and Grce, Ana and Milosavljević, Momir",
year = "2014",
abstract = "The relation between nanoscale structure, local atomic order and magnetic properties of (FeCoZr)(x)(CaF2)(100-x) (29 LT = x LT = 73 at. %) granular films is studied as a function of metal/insulator fraction ratio. The films of a thickness of 1-6 mu m were deposited on Al-foils and glass-ceramic substrates, by ion sputtering of targets of different metal/insulator contents. Structural characterization with X-ray and electron diffraction as well as transmission electron microscopy revealed that the films are composed of isolated nanocrystalline bcc alpha-FeCo(Zr) alloy and insulating fcc CaF2 matrix. They grow in a columnar structure, where elongated metallic nanograins are arranged on top of each other within the columns almost normal to the substrate surface. Mossbauer spectroscopy and magnetometry results indicate that their easy magnetization axes are oriented at an angle of 65 degrees-74 degrees to the surface in films with x between 46 and 74, above the electrical percolation threshold, which is attributed to the growth-induced shape anisotropy. Interatomic distances characteristic for metallic state of alpha-FeCo(Zr) nanograins were revealed by X-ray Absorption Spectroscopy. The results show a lack of surface oxidation of the alloy nanograins, so the growth-induced orientation of nanograins in the films cannot be attributed to this effect. The study is among the first to report a growth-induced non-planar magnetic anisotropy in metal/insulator granular films above the percolation threshold and to reveal the origin of it. (C) 2014 AIP Publishing LLC.",
journal = "Journal of Applied Physics",
title = "Growth-induced non-planar magnetic anisotropy in FeCoZr-CaF2 nanogranular films: Structural and magnetic characterization",
volume = "116",
number = "4",
doi = "10.1063/1.4891016"
}

Kasiuk, J. V., Fedotova, J. A., Przewoznik, J., Zukrowski, J., Sikora, M., Kapusta, C., Grce, A.,& Milosavljević, M.. (2014). Growth-induced non-planar magnetic anisotropy in FeCoZr-CaF2 nanogranular films: Structural and magnetic characterization. in Journal of Applied Physics, 116(4).
https://doi.org/10.1063/1.4891016

Kasiuk JV, Fedotova JA, Przewoznik J, Zukrowski J, Sikora M, Kapusta C, Grce A, Milosavljević M. Growth-induced non-planar magnetic anisotropy in FeCoZr-CaF2 nanogranular films: Structural and magnetic characterization. in Journal of Applied Physics. 2014;116(4).
doi:10.1063/1.4891016 .

Kasiuk, J. V., Fedotova, J. A., Przewoznik, J., Zukrowski, J., Sikora, M., Kapusta, Cz, Grce, Ana, Milosavljević, Momir, "Growth-induced non-planar magnetic anisotropy in FeCoZr-CaF2 nanogranular films: Structural and magnetic characterization" in Journal of Applied Physics, 116, no. 4 (2014),
https://doi.org/10.1063/1.4891016 . .

TY  - JOUR
AU  - Fedotova, J. A.
AU  - Przewoznik, J.
AU  - Kapusta, Cz
AU  - Milosavljević, Momir
AU  - Kasiuk, J. V.
AU  - Zukrowski, J.
AU  - Sikora, M.
AU  - Maximenko, A. A.
AU  - Szepietowska, D.
AU  - Homewood, Kevin P.
PY  - 2011
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4609
AB  - Temperature and magnetic field dependences of electrical conductivity are systematically studied in granular films (Fe45Co45Zr10)(x)(Al2O3)(100-x) (28 LT = x LT = 64) containing crystalline metallic alpha-FeCo-based nanoalloy cores encapsulated in an amorphous oxide shell embedded in an amorphous Al2O3 matrix. Formation of metallic core-oxide shell nanogranules is confirmed by transmission electron microscopy (TEM) and HRTEM. The structure of core and shell is governed with the difference in the oxidation states of Fe and Co ions investigated with EXAFS, XANES and Mossbauer spectroscopy. A considerable negative magnetoresistance (MR) effect of spin-dependent nature is observed in the whole range of x values. Its increase with decreasing temperature is correlated with the magnetic saturation of superparamagnetic metallic nanogranules. The enhanced MR effect in core-shell granular films is related to the percolation of oxide shells and their influence through spin filtering processes. A considerable high field MR at low temperatures and the resulting deviation of MR and squared magnetization are attributed to a magnetic randomness and/or strong magnetic anisotropy of the magnetic oxide shell.
T2  - Journal of Physics. D: Applied Physics
T1  - Magnetoresistance in FeCoZr-Al2O3 nanocomposite films containing metal core-oxide shell nanogranules
VL  - 44
IS  - 49
DO  - 10.1088/0022-3727/44/49/495001
ER  - 

@article{
author = "Fedotova, J. A. and Przewoznik, J. and Kapusta, Cz and Milosavljević, Momir and Kasiuk, J. V. and Zukrowski, J. and Sikora, M. and Maximenko, A. A. and Szepietowska, D. and Homewood, Kevin P.",
year = "2011",
abstract = "Temperature and magnetic field dependences of electrical conductivity are systematically studied in granular films (Fe45Co45Zr10)(x)(Al2O3)(100-x) (28 LT = x LT = 64) containing crystalline metallic alpha-FeCo-based nanoalloy cores encapsulated in an amorphous oxide shell embedded in an amorphous Al2O3 matrix. Formation of metallic core-oxide shell nanogranules is confirmed by transmission electron microscopy (TEM) and HRTEM. The structure of core and shell is governed with the difference in the oxidation states of Fe and Co ions investigated with EXAFS, XANES and Mossbauer spectroscopy. A considerable negative magnetoresistance (MR) effect of spin-dependent nature is observed in the whole range of x values. Its increase with decreasing temperature is correlated with the magnetic saturation of superparamagnetic metallic nanogranules. The enhanced MR effect in core-shell granular films is related to the percolation of oxide shells and their influence through spin filtering processes. A considerable high field MR at low temperatures and the resulting deviation of MR and squared magnetization are attributed to a magnetic randomness and/or strong magnetic anisotropy of the magnetic oxide shell.",
journal = "Journal of Physics. D: Applied Physics",
title = "Magnetoresistance in FeCoZr-Al2O3 nanocomposite films containing metal core-oxide shell nanogranules",
volume = "44",
number = "49",
doi = "10.1088/0022-3727/44/49/495001"
}

Fedotova, J. A., Przewoznik, J., Kapusta, C., Milosavljević, M., Kasiuk, J. V., Zukrowski, J., Sikora, M., Maximenko, A. A., Szepietowska, D.,& Homewood, K. P.. (2011). Magnetoresistance in FeCoZr-Al2O3 nanocomposite films containing metal core-oxide shell nanogranules. in Journal of Physics. D: Applied Physics, 44(49).
https://doi.org/10.1088/0022-3727/44/49/495001

Fedotova JA, Przewoznik J, Kapusta C, Milosavljević M, Kasiuk JV, Zukrowski J, Sikora M, Maximenko AA, Szepietowska D, Homewood KP. Magnetoresistance in FeCoZr-Al2O3 nanocomposite films containing metal core-oxide shell nanogranules. in Journal of Physics. D: Applied Physics. 2011;44(49).
doi:10.1088/0022-3727/44/49/495001 .

Fedotova, J. A., Przewoznik, J., Kapusta, Cz, Milosavljević, Momir, Kasiuk, J. V., Zukrowski, J., Sikora, M., Maximenko, A. A., Szepietowska, D., Homewood, Kevin P., "Magnetoresistance in FeCoZr-Al2O3 nanocomposite films containing metal core-oxide shell nanogranules" in Journal of Physics. D: Applied Physics, 44, no. 49 (2011),
https://doi.org/10.1088/0022-3727/44/49/495001 . .