Electronic structures of perovskite BaTbO3 studied by the LSDA +U method

The electronic and magnetic properties of BaTbO3 are studied by using the local-spin density approximation method where on-site Coulomb interaction U is included. The ground magnetic phase is found to be G-type antiferromagnetic with lattice constant of 4.278 A, which is consistent with experimental results. The states of Ba in the compound show obvious ionic characteristic, while very strong hybridization between Tb 4f and O 2p orbitals is found in the compound. The on-site Coulomb interaction U is found to have significant influences on the state distribution of Tb 4f. With the increase of U, most of the spin-up and spin-down states of Tb 4f move away from the Fermi level drastically, giving rise to the change of band gap of the compound and the variation of magnetic moment of Tb ions. The optimized value of U is determined to be 4.0 eV, and the corresponding band gap of BaTbO3 is 0.61 eV, which seems to be a narrow gap semiconductor rather than a good insulator.