On the mechanism for orbital-ordering in KCuF3

Pavarini, E.; Koch, E.; Lichtenstein, A. I.

On the mechanism for orbital-ordering in KCuF3

Authors

Pavarini, E.

Koch, E.

Lichtenstein, A. I.

Description

The Mott insulating perovskite KCuF3 is considered the archetype of an orbitally-ordered system. By using the LDA+dynamical mean-field theory (DMFT) method, we investigate the mechanism for orbital-ordering (OO) in this material. We show that the purely electronic Kugel-Khomskii super-exchange mechanism (KK) alone leads to a remarkably large transition temperature of T_KK about 350 K. However, orbital-order is experimentally believed to persist to at least 800 K. Thus Jahn-Teller distortions are essential for stabilizing orbital-order at such high temperatures.
4 pages, 5 figures