GGA+U calculations of correlated spin excitations in LaCoO.sub.3./sub..

0331997 - FZÚ 2010 RIV US eng J - Journal Article
Knížek, Karel - Jirák, Zdeněk - Hejtmánek, Jiří - Novák, Pavel - Ku, W.
GGA+U calculations of correlated spin excitations in LaCoO₃.
[GGA+U výpočty korelovaných spinových excitací v LaCoO₃.]
Physical Review. B. Roč. 79, č. 1 (2009), 014430/1-014430/8. ISSN 1098-0121
R&D Projects: GA ČR GA202/06/0051; GA AV ČR IAA100100611
Institutional research plan: CEZ:AV0Z10100521
Keywords : ground states * lanthanum compounds * magnetic structure * spin systems
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.475, year: 2009

GGA+U calculation study of many various Co3+ spin configurations for the model structures of LaCoO3 was performed. In addition to the nonmagnetic ground state based on the low-spin (LS) Co3+, the calculations evidence a number of stationary states based on the combinations of LS, high-spin (HS), and intermediate-spin (IS) Co3+ species. The stability of individual spin states is strongly conditioned by the character of neighboring spin states. If the amount of excited magnetic Co3+ ions in the LS matrix is small, their state is always of the HS kind. With an increasing number of Co3+ in HS states, a preference for antiparallel orientation of their spins appears and, at the same time, strong HS-HS nearest-neighbor correlations are evidenced. When the HS population in the LS matrix approaches a theoretical limit 1:1, further excitation to the HS state is hindered and alternative configurations based on clustering of the IS states become energetically favorable.

Byly provedeny GGA+U výpočty mnoha různých spinových konfigurací Co3+ pro modelové struktury LaCoO3. Stabilita jednotlivých spinových stavů je silně podmíněna charakterem sousedních spinů. Stav vysokého spinu je podmíněn stavem nízkého spinu na okolních kationtech Co3+, zatímco stav středního spinu je stabilizován přítomností stejného spinu v jeho okolí. Výpočty jsou ve shodě s modelem LS-LS/HS-IS spinových excitací Co3+.
Permanent Link: http://hdl.handle.net/11104/0177363