Re-examination of half-metallic ferromagnetism for doped LaMnO3 in quasiparticle self-consistent GW method

12 February 2009 (Thur), 10:00 am - 11:30 am

6F seminar room, Central Bldg., Sengen site

Prof. Takao Kotani (小谷岳生教授)

Department of Applied Mathematics and Physics, Tottori University (鳥取大学大学院工学研究科)

Re-examination of half-metallic ferromagnetism for doped LaMnO3 in quasiparticle self-consistent GW method

In this talk, we first describe the quasiparticle self-consistent GW (QSGW ) method, which can treat wide range of materials very well. Especially, we applied it to MnO and NiO, and have recently calculated their spin wave dispersions based on the QSGW [1]. They are in good agreement with experiments. Then we now apply it to a cubic virtual-crystal alloy La1-xBaxMnO3 (LBMO) as a theoretical representative for colossal magnetoresistive perovskite manganites. The QSGW predicts LBMO 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 calculated spin wave (SW) are very low in comparison with experiments. This is affected neither by rhombohedral deformation nor the intrinsic deficiency in the QSGW method. Thus it will be necessary to include effects due to phonons, which is not included in our calculation, so as to reproduce the experimental SW energies.

[1] T. Kotani and M. van Schilfgaarde,J. Phys.: Condens. Matter 20, 295214 (2008).

[2] T. Kotani and H.Kino,arXiv:0812.4294.

Dr. Hiori Kino(木野日織）