Theoretical prediction of Jahn-Teller distortions and orbital ordering in Cs2CuCl2Br2

Abstract

With the use of density function calculations we show that the actual crystal structure of Cs 2CuCl 2Br 2 should contain elongated in the ab-plane CuCl 4Br 2 octahedra, in contrast to the experimentally observed compression in the c direction. We also predict that the spins on Cu2 + ions should be ferromagnetically ordered in the ab plane, while the exchange interaction along the c direction is small and its sign is uncertain. © 2012 American Physical Society.