Electronic structure of Bi₂CuO₄ with antiferromagnetic spin ordering

Abstract

The electronic structure of antiferromagnetic Bi₂CuO₄ 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 Bi₂CuO₄ 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 Γ-point. This means that antiferromagnetic Bi₂CuO₄ is an indirect energy gap material. The calculated total density of states of Bi₂CuO₄ 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_x²_-y² orbitals. The magnetic moment at Cu sites is calculated to be 0.72 μ_B, which is close to experimental values.