Electronic structure of Bi_2CuO_4 with antiferromagnetic spin ordering

概要

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The electronic structure of antiferromagnetic Bi_2CUO_4 is calculated by using generalized gradient approximation considering on-site Coulomb interaction between d-electrons (GGA+U). The GGA+U calculation indicates clearly that the antiferromagnetic phase is the stablest among non-magnetic, ferromagnetic and antiferromagnetic phases. By using U parameter (7.48 eV) and J parameter (0.95 eV), the band gap energy of Bi_2CuO_4 is calculated to be ca. 2.4 eV, which is comparable to the experimental one. The valence band maximum is approximately located at the X-point and the conduction band minimum at the F-point. This means that antiferromagnetic Bi_2CuO_4 is an indirect energy gap material. The calculated total density of states of Bi_2CuO_4 well corresponds to the state density experimentally deduced by x-ray photoelectron and electron-energy-loss spectroscopy. Also, it is found from the partial density of states analysis that the top of the valence band is mainly formed by O 2p orbitals, whereas the lower conduction band mainly consists of Cu 3d_x^2_<-y>^2 orbitals. The magnetic moment at Cu sites is calculated to be 0.72 μ_B, which is close to experimental values.
社団法人日本セラミックス協会の論文
2008-04-01