Universität zu Köln

Gapontsev, Vladimir V., Khomskii, Daniel I. and Streltsov, Sergey V. (2016). Magnetism and charge ordering in high- and low-temperature phases of Nb2O2F3. J. Magn. Magn. Mater., 420. S. 28 - 33. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1873-4766

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Abstract

It is shown using ab initio band structure calculations that Nb2O2F3 is in the orbital-selective regime in the high -temperature phase (T>90 K), when two electrons occupy singlet molecular orbital, while the magnetic response comes from the remaining single electron in NW23.5+ dimer. The charge order occurs at low temperatures, resulting in the formation of Nb3+-Nb3+- and Nb4+-Nb4+ dimers, which makes this system nonmagnetic. The single electron with unpaired spin is transferred to Nb3+ -Nb3+ dimer, but due to a strong splitting of the bonding xz/yz molecular orbitals the low-spin state with S=0 is stabilized. We argue that the mechanism of the charge ordering in Nb2O2F3 is the gain in kinetic energy related to the formation of molecular orbitals, which occurs due to a strong nonlinear distance dependence of the hopping parameters. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Gapontsev, Vladimir V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Khomskii, Daniel I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Streltsov, Sergey V. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-252536
DOI:	10.1016/j.jmmm.2016.06.084
Journal or Publication Title:	J. Magn. Magn. Mater.
Volume:	420
Page Range:	S. 28 - 33
Date:	2016
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1873-4766
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language STRONGLY CORRELATED SYSTEMS; ELECTRONIC-STRUCTURE; TRANSITIONS; CRYSTAL; SPECTRA Multiple languages Materials Science, Multidisciplinary; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/25253