First principle research of possible HM-AFM in double perovskites and A_2TcReO_6 (A = Si, Ge, Sn, and Pb) with group IVA elements set on the A-site position

摘要

We calculated electronic structures of double perovskite structures of A_2MoOsO_6 and A_2TcReO_6 (A= Si, Ge, Sn, and Pb) based on the density functional theory which was carried out with a full structural optimization using generalized gradient approximation and taking into account the correlation effect (GGA + U). In GGA calculation, Pb_2TcReO_6 shows a half-metallic antiferromagnet (HM-AFM) character istic, whereas Sn_2MoOsO_6, Pb_2MoOsO_6, and Sn_2TcReO_6 are nearly HM-AFMs. With GGA + U calculation, Sn_2MoOsO_6 and Pb_2MoOsO_6 become stable HM-AFM, but Sn_2TcRe0_6 and Pb_2TcRe0_6 changes HM-AFM into an antiferromagnetic insulator. The p-d hybridization between B(B')_d-O_p and double exchange interaction is the mean reason to result in the half-metallic and compensated ferrimagnetic phase.