KFU. Card publication. Density Functional Theory Approach to the Vibrational Properties and Magnetic Specific Heat of the Covalent Chain Antiferromagnet KFeS2

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DENSITY FUNCTIONAL THEORY APPROACH TO THE VIBRATIONAL PROPERTIES AND MAGNETIC SPECIFIC HEAT OF THE COVALENT CHAIN ANTIFERROMAGNET KFES2

Form of presentation

Articles in international journals and collections

Year of publication

2022

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Authors, employees of KFU

Vagizov Farit Gabdulkhakovich, author

Kiyamov Ayrat Gazinurovich, author

Kuznecov Maksim Dmitrievich, author

Tagirov Lenar Rafgatovich, author

Tayurskiy Dmitriy Albertovich, author

Bibliographic description in the original language

Kiiamov A, Kuznetsov M, Croitori D, Density Functional Theory Approach to the Vibrational Properties and Magnetic Specific Heat of the Covalent Chain Antiferromagnet KFeS2//Molecules. - 2022. - Vol.27, Is.9. - Art. �2663.

Annotation

Ternary potassium-iron sulfide, KFeS2, belongs to the family of highly anisotropic quasi-one-dimensional antiferromagnets with unusual «anti-Curie-Weiss« susceptibility, quasi-linearly growing with a rising temperature up to 700 K, an almost vanishing magnetic contribution to the specific heat, drastically reduced magnetic moment, etc. While some of the measurements can be satisfactorily described, the deficiency of the entropy changes upon the magnetic transition and the spin state of the iron ion remains a challenge for the further understanding of magnetism. In this work, high-quality single-crystalline samples of KFeS2 were grown by the Bridgman method, and their stoichiometry, crystal structure, and absence of alien magnetic phases were checked, utilizing wavelength dispersive X-ray electron-probe microanalysis, powder X-ray diffraction, and Fe Mossbauer spectroscopy, respectively. An ab initio approach was developed to calculate the thermodynamic properties of KFeS2. The element-specific phonon modes and their density of states (PDOS) were calculated applying the density functional theory in the DFT + U version, which explicitly takes into account the on-site Coulomb repulsion U of electrons and their exchange interaction J. The necessary calibration of the frequency scale was carried out by comparison with the experimental iron PDOS derived from the inelastic nuclear scattering experiment. The infrared absorption measurements confirmed the presence of two high-frequency peaks consistent with the calculated PDOS. The calibrated PDOS allowed the calculation of the lattice contribution to the specific heat of KFeS2 by direct summation over the phonon modes without approximations and adjustable parameters. The temperature-dependent magnetic specific heat evaluated by subtraction of the calculated phonon contribution from the experimental specific heat provides a lower boundary for estimating the reduced spin state of the iron ion.

Keywords

ternary potassium-iron sulfide, quasi-one-dimensional antiferromagnet, density functional theory, phonon density of states, magnetic specific heat, spin chain models

The name of the journal

Molecules

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85129267077&doi=10.3390%2fmolecules27092663&partnerID=40&md5=f23caa65db983e4decce624f4f3ab5c3

Please use this ID to quote from or refer to the card

https://repository.kpfu.ru/eng/?p_id=266559&p_lang=2

Full metadata record

Field DC	Value	Language
dc.contributor.author	Vagizov Farit Gabdulkhakovich	ru_RU
dc.contributor.author	Kiyamov Ayrat Gazinurovich	ru_RU
dc.contributor.author	Kuznecov Maksim Dmitrievich	ru_RU
dc.contributor.author	Tagirov Lenar Rafgatovich	ru_RU
dc.contributor.author	Tayurskiy Dmitriy Albertovich	ru_RU
dc.date.accessioned	2022-01-01T00:00:00Z	ru_RU
dc.date.available	2022-01-01T00:00:00Z	ru_RU
dc.date.issued	2022	ru_RU
dc.identifier.citation	Kiiamov A, Kuznetsov M, Croitori D, Density Functional Theory Approach to the Vibrational Properties and Magnetic Specific Heat of the Covalent Chain Antiferromagnet KFeS2//Molecules. - 2022. - Vol.27, Is.9. - Art. �2663.	ru_RU
dc.identifier.uri	https://repository.kpfu.ru/eng/?p_id=266559&p_lang=2	ru_RU
dc.description.abstract	Molecules	ru_RU
dc.description.abstract	Ternary potassium-iron sulfide, KFeS2, belongs to the family of highly anisotropic quasi-one-dimensional antiferromagnets with unusual «anti-Curie-Weiss« susceptibility, quasi-linearly growing with a rising temperature up to 700 K, an almost vanishing magnetic contribution to the specific heat, drastically reduced magnetic moment, etc. While some of the measurements can be satisfactorily described, the deficiency of the entropy changes upon the magnetic transition and the spin state of the iron ion remains a challenge for the further understanding of magnetism. In this work, high-quality single-crystalline samples of KFeS2 were grown by the Bridgman method, and their stoichiometry, crystal structure, and absence of alien magnetic phases were checked, utilizing wavelength dispersive X-ray electron-probe microanalysis, powder X-ray diffraction, and Fe Mossbauer spectroscopy, respectively. An ab initio approach was developed to calculate the thermodynamic properties of KFeS2. The element-specific phonon modes and their density of states (PDOS) were calculated applying the density functional theory in the DFT + U version, which explicitly takes into account the on-site Coulomb repulsion U of electrons and their exchange interaction J. The necessary calibration of the frequency scale was carried out by comparison with the experimental iron PDOS derived from the inelastic nuclear scattering experiment. The infrared absorption measurements confirmed the presence of two high-frequency peaks consistent with the calculated PDOS. The calibrated PDOS allowed the calculation of the lattice contribution to the specific heat of KFeS2 by direct summation over the phonon modes without approximations and adjustable parameters. The temperature-dependent magnetic specific heat evaluated by subtraction of the calculated phonon contribution from the experimental specific heat provides a lower boundary for estimating the reduced spin state of the iron ion.	ru_RU
dc.language.iso	ru	ru_RU
dc.subject	ternary potassium-iron sulfide	ru_RU
dc.subject	quasi-one-dimensional antiferromagnet	ru_RU
dc.subject	density functional theory	ru_RU
dc.subject	phonon density of states	ru_RU
dc.subject	magnetic specific heat	ru_RU
dc.subject	spin chain models	ru_RU
dc.title	Density Functional Theory Approach to the Vibrational Properties and Magnetic Specific Heat of the Covalent Chain Antiferromagnet KFeS2	ru_RU
dc.type	Articles in international journals and collections	ru_RU