Investigation of possible half-metallic antiferromagnets on double perovskites A2BB`O6 (A=Ca, Sr Ba; B,B`=TransitionMetal Elements)

Abstract

A search was made for possible half-metallic (HM) antiferromagnet (AFM) in all the (C29 2 =406) double perovskites structures of Sr2BB`O6 where BB` pairs are any combination of 3d, 4d or 5d transition elements with the exception of La. Sr can also be replaced by Ca or Ba whenever HM-AFM was found and similar calculations were then performed in order to probe further possibilities. It was found that A2MoOsO6, A2TcReO6, A2CrRuO6, where A=Ca, Sr, Ba, are all potential candidates for HM-AFM. The AFM of A2BB`O6 comes from both the superexchange mechanism and the generalized double exchange mechanism via the B(t2g)-O2pp-B`(t2g) coupling, With the latter also being the origin of their HM. Also considered were the effects of spin-orbit coupling (SOC) and correlation (+U) by introducing +SOC and +U corrections. It is found that the SOC effect has much less influence than the correlation effect on the HMproperty of the compounds. For A2TcReO6 and A2CrRuO6, after +U, they become nearlyMott- Insulators. In the future, it is hoped that therewill be further experimental confirmation for these possible HM-AFMcandidates. © 2013 Global-Science Press.