Unusual magnetic behavior of cubic double perovskite Ba2YIrO6 with Ir5+(5d4) ions

- Using density functional calculations, we investigate the electronic structure and magnetism of double-perovskite Ba2YIrO6 to explore the origin of its unusual magnetic behavior. Our results show that the breakdown of expected j = 0 nonmagnetic state of Ir5+(5d4) in Ba2YIrO6 is induced by both bandwidth and exchange interaction. In addition, the bandwidth effect makes the system behave like metal, while the antiferromagnetic interaction between Ir ions should be responsible for the insulator behavior. Moreover, the strong geometrical frustration in Ir triangular unit prevents the formation of long-range magnetic order.