Tb0.5Bi0.5MnO3:: New material.: A DFT study

In the present work we have determined the band structure and the densities of states (DOS) of Tb0.5Bi0.5MnO3 in cubic phase using the density functional theory (DFT). The determination of the lattice constant was made by minimizing the energy as a function of volume. The internal coordinate of the O-atom was optimized. From these optimizations we have found that the lattice constant is 8.482 angstrom and the bond length between Tb and O-atoms is 2.193 angstrom and the one for Bi and O-atoms is 2.051 angstrom. From a study of the DOS of f-Tb, e(g) and t(2g)-Mn atomic-like orbitals for each spin polarization we conclude that there exists a permanent magnetic moment of about 16 Bohr magneton per unit cell. Also, a metallic behavior is displayed, and thus it is expected that ferroelectricity will disappear. Inside the conduction band, next to Fermi level, two peaks in the DOS-spin-down are observed, which are due to f-Tb. Therefore, conduction electrons will be spin-down polarized and this shows that Tb0.5Bi0.5MnO3 has possible applications in spintronics. (C) 2007 Elsevier Ltd. All rights reserved.