TY  - JOUR
AU  - Martin, Catalin
AU  - Martinez, V. A.
AU  - Opačić, Marko R.
AU  - Đurđić-Mijin, Sanja
AU  - Mitrić, Petar
AU  - Umićević, Ana
AU  - Poudel, A.
AU  - Sydoryk, Ihor
AU  - Ren, Weijun
AU  - Martin, Ruaridh M.
AU  - Tanner, David B.
AU  - Lazarević, Nenad
AU  - Petrović, Čedomir
AU  - Tanasković, Darko
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10987
AB  - Intermetallic narrow-gap semiconductors have been intensively explored due to their large thermoelectric power at low temperatures and a possible role of strong electronic correlations in their unusual thermodynamic and transport properties. Here we study the optical spectra and vibrational properties of FeGa3 single crystal. The optical conductivity indicates that FeGa3 has a direct band gap of ≈0.7 eV, consistent with density functional theory (DFT) calculations. Most importantly, we find a substantial spectral weight also below 0.4 eV, which is the energy of the indirect (charge) gap found in resistivity measurements and ab initio calculations. We find that the spectral weight below the gap decreases with increasing temperature, which indicates that it originates from the impurity states and not from the electronic correlations. Interestingly, we did not find any signatures of the impurity states in vibrational spectra. The infrared and Raman vibrational lines are narrow and weakly temperature dependent. The vibrational frequencies are in excellent agreement with our DFT calculations, implying a modest role of electronic correlations. Narrow Mössbauer spectral lines also indicate high crystallinity of the sample. © 2023 American Physical Society.
T2  - Physical Review B
T1  - Optical conductivity and vibrational spectra of the narrow-gap semiconductor FeGa3
VL  - 107
IS  - 16
DO  - 10.1103/PhysRevB.107.165151
ER  - 

@article{
author = "Martin, Catalin and Martinez, V. A. and Opačić, Marko R. and Đurđić-Mijin, Sanja and Mitrić, Petar and Umićević, Ana and Poudel, A. and Sydoryk, Ihor and Ren, Weijun and Martin, Ruaridh M. and Tanner, David B. and Lazarević, Nenad and Petrović, Čedomir and Tanasković, Darko",
year = "2023",
abstract = "Intermetallic narrow-gap semiconductors have been intensively explored due to their large thermoelectric power at low temperatures and a possible role of strong electronic correlations in their unusual thermodynamic and transport properties. Here we study the optical spectra and vibrational properties of FeGa3 single crystal. The optical conductivity indicates that FeGa3 has a direct band gap of ≈0.7 eV, consistent with density functional theory (DFT) calculations. Most importantly, we find a substantial spectral weight also below 0.4 eV, which is the energy of the indirect (charge) gap found in resistivity measurements and ab initio calculations. We find that the spectral weight below the gap decreases with increasing temperature, which indicates that it originates from the impurity states and not from the electronic correlations. Interestingly, we did not find any signatures of the impurity states in vibrational spectra. The infrared and Raman vibrational lines are narrow and weakly temperature dependent. The vibrational frequencies are in excellent agreement with our DFT calculations, implying a modest role of electronic correlations. Narrow Mössbauer spectral lines also indicate high crystallinity of the sample. © 2023 American Physical Society.",
journal = "Physical Review B",
title = "Optical conductivity and vibrational spectra of the narrow-gap semiconductor FeGa3",
volume = "107",
number = "16",
doi = "10.1103/PhysRevB.107.165151"
}

Martin, C., Martinez, V. A., Opačić, M. R., Đurđić-Mijin, S., Mitrić, P., Umićević, A., Poudel, A., Sydoryk, I., Ren, W., Martin, R. M., Tanner, D. B., Lazarević, N., Petrović, Č.,& Tanasković, D.. (2023). Optical conductivity and vibrational spectra of the narrow-gap semiconductor FeGa3. in Physical Review B, 107(16).
https://doi.org/10.1103/PhysRevB.107.165151

Martin C, Martinez VA, Opačić MR, Đurđić-Mijin S, Mitrić P, Umićević A, Poudel A, Sydoryk I, Ren W, Martin RM, Tanner DB, Lazarević N, Petrović Č, Tanasković D. Optical conductivity and vibrational spectra of the narrow-gap semiconductor FeGa3. in Physical Review B. 2023;107(16).
doi:10.1103/PhysRevB.107.165151 .

Martin, Catalin, Martinez, V. A., Opačić, Marko R., Đurđić-Mijin, Sanja, Mitrić, Petar, Umićević, Ana, Poudel, A., Sydoryk, Ihor, Ren, Weijun, Martin, Ruaridh M., Tanner, David B., Lazarević, Nenad, Petrović, Čedomir, Tanasković, Darko, "Optical conductivity and vibrational spectra of the narrow-gap semiconductor FeGa3" in Physical Review B, 107, no. 16 (2023),
https://doi.org/10.1103/PhysRevB.107.165151 . .

TY  - JOUR
AU  - Mravik, Željko
AU  - Bajuk-Bogdanović, Danica V.
AU  - Jovanović, Sonja
AU  - Rmuš, Jelena
AU  - Olejniczak, Andrzej
AU  - Mraković, Ana Đ.
AU  - Lazarević, Jasmina
AU  - Uskoković-Marković, Snežana
AU  - Lazarević, Nenad
AU  - Skuratov, Vladimir A.
AU  - Jovanović, Zoran
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10376
AB  - Ion beam irradiation is a versatile tool for structural modification andengineering of new materials. In this study, 12-tungstophosphoric acid (WPA)films of different thickness were spin-coated on platinized silicon substrate andirradiated with low energy hydrogen ions (10 keV) and swift heavy ions (Bi,Xe, and V) with energies up to 710 MeV. The different energy/fluence combi-nations allowed controllable structural changes that were investigated in detailusing Raman and Infrared spectroscopy. For 120-nm-thick WPA samples, theirradiation led to the decrease of intensity of the skeletal and W-Oc-W bands ofKeggin anion in order: Bi < V < Xe (for their applied energy/fluence combina-tion). Also, symmetry change of Keggin anion similar to the one observed inthe case of Keggin anions interacting with the supports was observed. For theselected ion beam irradiation parameters, xenon ion beam induced transforma-tion of WPA to polytungstate. For 20-μm-thick WPA samples, the irradiationwith hydrogen ion beam induced changes of skeletal vibrations and increasedindividualistic behavior of Keggin anions. As the fluence increased, theamount of the Keggin anions partially transformed to bronze also increased.Irradiation with vanadium also caused transformation to bronze-like structurebut with higher ratio of terminal W=Odbonds. The overall results show clearReceived: 9 February 2022Revised: 17 June 2022Accepted: 5 July 2022DOI: 10.1002/jrs.6423J Raman Spectrosc.2022;1–11.wileyonlinelibrary.com/journal/jrs© 2022 John Wiley & Sons Ltd.1correlation between degree of structural modification of WPA and thecalculated displacement per atom value. These results open possibilities forengineering new catalytically active structures of polyoxometalates with thehelp of ion beams.
T2  - Journal of Raman Spectroscopy
T1  - Modification of Keggin anion structure with ion beams—A new spectroscopic insights into the effects of keV- and MeV-ion beam irradiation on 12-tungstophosphoric acid
DO  - 10.1002/jrs.6423
ER  - 

@article{
author = "Mravik, Željko and Bajuk-Bogdanović, Danica V. and Jovanović, Sonja and Rmuš, Jelena and Olejniczak, Andrzej and Mraković, Ana Đ. and Lazarević, Jasmina and Uskoković-Marković, Snežana and Lazarević, Nenad and Skuratov, Vladimir A. and Jovanović, Zoran",
year = "2022",
abstract = "Ion beam irradiation is a versatile tool for structural modification andengineering of new materials. In this study, 12-tungstophosphoric acid (WPA)films of different thickness were spin-coated on platinized silicon substrate andirradiated with low energy hydrogen ions (10 keV) and swift heavy ions (Bi,Xe, and V) with energies up to 710 MeV. The different energy/fluence combi-nations allowed controllable structural changes that were investigated in detailusing Raman and Infrared spectroscopy. For 120-nm-thick WPA samples, theirradiation led to the decrease of intensity of the skeletal and W-Oc-W bands ofKeggin anion in order: Bi < V < Xe (for their applied energy/fluence combina-tion). Also, symmetry change of Keggin anion similar to the one observed inthe case of Keggin anions interacting with the supports was observed. For theselected ion beam irradiation parameters, xenon ion beam induced transforma-tion of WPA to polytungstate. For 20-μm-thick WPA samples, the irradiationwith hydrogen ion beam induced changes of skeletal vibrations and increasedindividualistic behavior of Keggin anions. As the fluence increased, theamount of the Keggin anions partially transformed to bronze also increased.Irradiation with vanadium also caused transformation to bronze-like structurebut with higher ratio of terminal W=Odbonds. The overall results show clearReceived: 9 February 2022Revised: 17 June 2022Accepted: 5 July 2022DOI: 10.1002/jrs.6423J Raman Spectrosc.2022;1–11.wileyonlinelibrary.com/journal/jrs© 2022 John Wiley & Sons Ltd.1correlation between degree of structural modification of WPA and thecalculated displacement per atom value. These results open possibilities forengineering new catalytically active structures of polyoxometalates with thehelp of ion beams.",
journal = "Journal of Raman Spectroscopy",
title = "Modification of Keggin anion structure with ion beams—A new spectroscopic insights into the effects of keV- and MeV-ion beam irradiation on 12-tungstophosphoric acid",
doi = "10.1002/jrs.6423"
}

Mravik, Ž., Bajuk-Bogdanović, D. V., Jovanović, S., Rmuš, J., Olejniczak, A., Mraković, A. Đ., Lazarević, J., Uskoković-Marković, S., Lazarević, N., Skuratov, V. A.,& Jovanović, Z.. (2022). Modification of Keggin anion structure with ion beams—A new spectroscopic insights into the effects of keV- and MeV-ion beam irradiation on 12-tungstophosphoric acid. in Journal of Raman Spectroscopy.
https://doi.org/10.1002/jrs.6423

Mravik Ž, Bajuk-Bogdanović DV, Jovanović S, Rmuš J, Olejniczak A, Mraković AĐ, Lazarević J, Uskoković-Marković S, Lazarević N, Skuratov VA, Jovanović Z. Modification of Keggin anion structure with ion beams—A new spectroscopic insights into the effects of keV- and MeV-ion beam irradiation on 12-tungstophosphoric acid. in Journal of Raman Spectroscopy. 2022;.
doi:10.1002/jrs.6423 .

Mravik, Željko, Bajuk-Bogdanović, Danica V., Jovanović, Sonja, Rmuš, Jelena, Olejniczak, Andrzej, Mraković, Ana Đ., Lazarević, Jasmina, Uskoković-Marković, Snežana, Lazarević, Nenad, Skuratov, Vladimir A., Jovanović, Zoran, "Modification of Keggin anion structure with ion beams—A new spectroscopic insights into the effects of keV- and MeV-ion beam irradiation on 12-tungstophosphoric acid" in Journal of Raman Spectroscopy (2022),
https://doi.org/10.1002/jrs.6423 . .

TY  - JOUR
AU  - Wang, Aifeng
AU  - Milosavljević, Ana
AU  - Abeykoon, A. M. Milinda
AU  - Ivanovski, Valentin N.
AU  - Du, Qianheng
AU  - Baum, Andreas
AU  - Stavitski, Eli
AU  - Liu, Yu
AU  - Lazarević, Nenad
AU  - Attenkofer, Klaus
AU  - Hackl, Rudi
AU  - Popović, Zoran
AU  - Petrović, Čedomir
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10380
AB  - Connections between crystal chemistry and critical temperature Tc have been in the focus of superconductivity, one of the most widely studied phenomena in physics, chemistry, and materials science alike. In most Fe-based superconductors, materials chemistry and physics conspire so that Tc correlates with the average anion height above the Fe plane, i.e., with the geometry of the FeAs4 or FeCh4 (Ch = Te, Se, or S) tetrahedron. By synthesizing Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1), we find that in alloyed crystals Tc is not correlated with the anion height like it is for most other Fe superconductors. Instead, changes in Tc(x) and tetragonal-to-orthorhombic (nematic) transition Ts(x) upon cooling are correlated with disorder in Fe vibrations in the direction orthogonal to Fe planes, along the crystallographic c-axis. The disorder stems from the random nature of S substitution, causing deformed Fe(Se,S)4 tetrahedra with different Fe–Se and Fe–S bond distances. Our results provide evidence of Tc and Ts suppression by disorder in anion height. The connection to local crystal chemistry may be exploited in computational prediction of new superconducting materials with FeSe/S building blocks.
T2  - Inorganic Chemistry
T1  - Suppression of Superconductivity and Nematic Order in Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder
VL  - 61
IS  - 29
SP  - 11036
EP  - 11045
DO  - 10.1021/acs.inorgchem.2c00568
ER  - 

@article{
author = "Wang, Aifeng and Milosavljević, Ana and Abeykoon, A. M. Milinda and Ivanovski, Valentin N. and Du, Qianheng and Baum, Andreas and Stavitski, Eli and Liu, Yu and Lazarević, Nenad and Attenkofer, Klaus and Hackl, Rudi and Popović, Zoran and Petrović, Čedomir",
year = "2022",
abstract = "Connections between crystal chemistry and critical temperature Tc have been in the focus of superconductivity, one of the most widely studied phenomena in physics, chemistry, and materials science alike. In most Fe-based superconductors, materials chemistry and physics conspire so that Tc correlates with the average anion height above the Fe plane, i.e., with the geometry of the FeAs4 or FeCh4 (Ch = Te, Se, or S) tetrahedron. By synthesizing Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1), we find that in alloyed crystals Tc is not correlated with the anion height like it is for most other Fe superconductors. Instead, changes in Tc(x) and tetragonal-to-orthorhombic (nematic) transition Ts(x) upon cooling are correlated with disorder in Fe vibrations in the direction orthogonal to Fe planes, along the crystallographic c-axis. The disorder stems from the random nature of S substitution, causing deformed Fe(Se,S)4 tetrahedra with different Fe–Se and Fe–S bond distances. Our results provide evidence of Tc and Ts suppression by disorder in anion height. The connection to local crystal chemistry may be exploited in computational prediction of new superconducting materials with FeSe/S building blocks.",
journal = "Inorganic Chemistry",
title = "Suppression of Superconductivity and Nematic Order in Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder",
volume = "61",
number = "29",
pages = "11036-11045",
doi = "10.1021/acs.inorgchem.2c00568"
}

Wang, A., Milosavljević, A., Abeykoon, A. M. M., Ivanovski, V. N., Du, Q., Baum, A., Stavitski, E., Liu, Y., Lazarević, N., Attenkofer, K., Hackl, R., Popović, Z.,& Petrović, Č.. (2022). Suppression of Superconductivity and Nematic Order in Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder. in Inorganic Chemistry, 61(29), 11036-11045.
https://doi.org/10.1021/acs.inorgchem.2c00568

Wang A, Milosavljević A, Abeykoon AMM, Ivanovski VN, Du Q, Baum A, Stavitski E, Liu Y, Lazarević N, Attenkofer K, Hackl R, Popović Z, Petrović Č. Suppression of Superconductivity and Nematic Order in Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder. in Inorganic Chemistry. 2022;61(29):11036-11045.
doi:10.1021/acs.inorgchem.2c00568 .

Wang, Aifeng, Milosavljević, Ana, Abeykoon, A. M. Milinda, Ivanovski, Valentin N., Du, Qianheng, Baum, Andreas, Stavitski, Eli, Liu, Yu, Lazarević, Nenad, Attenkofer, Klaus, Hackl, Rudi, Popović, Zoran, Petrović, Čedomir, "Suppression of Superconductivity and Nematic Order in Fe1–ySe1–xSx (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder" in Inorganic Chemistry, 61, no. 29 (2022):11036-11045,
https://doi.org/10.1021/acs.inorgchem.2c00568 . .