Universität zu Köln

Streltsov, S. V., Pchelkina, Z. V., Khomskii, D. I., Skorikov, N. A., Anokhin, A. O., Shvachko, Yu. N., Korotin, M. A., Anisimov, V. I. and Ustinov, V. V. (2014). Nature of the ferromagnetic ground state in the Mn-4 molecular magnet. Phys. Rev. B, 89 (1). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9969

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Abstract

Using ab initio band-structure and model calculations, we studied magnetic properties of one of the Mn-4 molecular magnets [Mn-4(hmp)(6)], where two types of the Mn ions exist: Mn3+ and Mn2+. The direct calculation of the exchange constants in the GGA+U approximation shows that in contrast to a common belief, the strongest exchange coupling is not between two Mn3+ ions (J(bb)), but along two out of four exchange paths connecting Mn3+ and Mn2+ ions (J(wb)). Within the perturbation theory, we performed the microscopic analysis of different contributions to the exchange constants, which allows us to establish the mechanism for the largest ferromagnetic exchange. In the presence of the charge order, the lowest in energy virtual excitations, contributing to the superexchange, will not be those across the Hubbard gap similar to U, but will be those between the Mn3+ and Mn4+ ions, which cost much smaller energy V (<< U). Together with strong Hund's rule coupling and specific orbital order, this leads to large ferromagnetic exchange interaction for two out of four Mn2+-Mn3+ pairs.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Streltsov, S. V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pchelkina, Z. V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Khomskii, D. I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Skorikov, N. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Anokhin, A. O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Shvachko, Yu. N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Korotin, M. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Anisimov, V. I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ustinov, V. V. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-448091
DOI:	10.1103/PhysRevB.89.014427
Journal or Publication Title:	Phys. Rev. B
Volume:	89
Number:	1
Date:	2014
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9969
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ELECTRONIC-STRUCTURE; RELAXATION; COMPLEXES Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/44809