Re-examination of half-metallic ferromagnetism for doped LaMnO(3) in a quasiparticle self-consistent GW method.

We apply the quasiparticle self-consistent GW (QSGW) method to a cubic virtual-crystal alloy La(1-x)Ba(x)MnO(3) as a theoretical representative for colossal magnetoresistive perovskite manganites. The QSGW predicts it as a fully polarized half-metallic ferromagnet for a wide range of x and lattice constant. Calculated density of states and dielectric functions are consistent with experiments. In contrast, the energies of the calculated spin wave are very low in comparison with experiments. This is affected neither by rhombohedral deformation nor the intrinsic deficiency in the QSGW method. Thus we end up with a conjecture that phonons related to the Jahn-Teller distortion should hybridize with spin waves more strongly than people thought until now.