title: A class of rare antiferromagnetic metallic oxides: double perovskite AMn3V4O12 (A = Na(+), Ca(2+), and La(3+)) and the site-selective doping effect.
abstract: We have investigated the structural, electronic, and magnetic properties of A-site-ordered double-perovskite-structured oxides, AA'3B4O12 (A = Na, Ca, and La) with Mn and V at A' and B sites, respectively, using first-principle calculations based on the density functional theory. Our calculation results show that the antiferromagnetic phase is the ground state for all the compounds. By changing the A-site ions from Na(+) to Ca(2+) and then to La(3+), the transfer of charge between Mn and O ions was changed from 1.56 to 1.55 and then to 1.50, and that between the V and O ions changed from 2.01 to 1.95 and then to 1.93, revealing the cause for the unusual site-selective doping effect. Mn 3d electrons dominate the magnetic moment and are localized, with an intense hybridization with O 2p orbitals, which indicates that the magnetic exchange interaction between Mn ions is mediated through O and that the super exchange mechanism will take effect. These materials have a large one-electron bandwidth W, and the ratio of the on-site Coulomb repulsion U to W is less than the critical value (U/W)c, which leads to metallic behavior of AMn3V4O12. This is further evidenced by the large number of free electrons contributed by V at the Fermi surface. These calculations, in combination with the reported experimental data, prove that these double perovskites belong to the rare antiferromagnetic metallic oxides.
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng, 475004, People's Republic of China. wangyx@henu.edu.cn.
authors.forename: Guangbiao
authors.initials: G
authors.lastname: Zhang
authors.forename: Yuanxu
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhenxiang
authors.initials: Z
authors.lastname: Cheng
authors.forename: Yuli
authors.initials: Y
authors.lastname: Yan
authors.forename: Chengxiao
authors.initials: C
authors.lastname: Peng
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Shuai
authors.initials: S
authors.lastname: Dong