Evaluation of half-metallic antiferromagnetism in A(2)CrFeO(6) (A = La, Sr)

초록

The nearly well-ordered double perovskite La2CrFeO6 has been synthesized recently. Contrary to previous theoretical predictions, but in agreement with experimental observations, our first principle calculations indicate an insulating ferrimagnet La2CrFeO6 with antialigned S = 3/2 Cr3+ and S = 5/2 Fe3+ ions, using the local spin density approximation (LSDA), a correlated band theory LDA + U, and the Tran-Blaha modified Becke-Johnson method. Additionally, we investigated the double perovskite Sr2CrFeO6, which is as yet unsynthesized. In LSDA calculations, this system shows formally tetravalent Cr and Fe ions both having antialigned S = 1 moments, but is a simple metal. Once applying on-site Coulomb repulsion U on both Cr and Fe ions, this system becomes half metallic and the moment of Fe is substantially reduced, resulting in zero net moment. These results are consistent with our fixed spin moment studies. Our results suggest a precisely compensated half-metallic Sr2CrFeO6.