Journal Article

FZJ-2020-03814

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Origin of orbital ordering in YTiO 3 and LaTiO 3

Zhang, X.-J.FZJ* ; Koch, E. (Corresponding author)FZJ* ; Pavarini, E.FZJ*

2020
Woodbury, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/26678  doi:10.1103/PhysRevB.102.035113

Abstract: The origin of orbital order in correlated transition-metal compounds is strongly debated. For the paradigmatic $e_g$ systems $KCuF_3$ and $LaMnO_3$, it has been shown that the electronic Kugel'-Khomskii mechanism alone is not sufficient to drive the orbital-ordering transition up to the high temperatures at which it is experimentally observed. In the case of $t_{2g}$ compounds, however, the role played by the superexchange interaction remains unclear. Here we investigate this question for two representative systems, the $3dt^1_{2g}$ Mott insulators $LaTiO_3$ and $YTiO_3$. We show that the Kugel'-Khomskii superexchange transition temperature $T_{KK}$ is unexpectedly large, comparable to the value for the $e^3_g$ fluoride $KCuF_3$. By deriving the general form of the orbital superexchange Hamiltonian for the $t^1_{2g}$ configuration, we show that the $GdFeO_3$-type distortion plays a key part in enhancing $T_{KK}$ to about 300 K. Still, orbital ordering above 300 K can be ascribed only to the presence of a static crystal-field splitting.

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Contributing Institute(s):

1. Jülich Supercomputing Center (JSC)
2. Theoretische Nanoelektronik (IAS-3)
3. JARA - HPC (JARA-HPC)

Research Program(s):

1. 511 - Computational Science and Mathematical Methods (POF3-511) (POF3-511)
2. 144 - Controlling Collective States (POF3-144) (POF3-144)
3. Charge-transfer effects in multi-orbital correlated systems (jiff46_20191101) (jiff46_20191101)

Appears in the scientific report 2020

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Electronics and Telecommunications Collection ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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