Magnetic ordering, orbital ordering, and resonant x-ray scattering in perovskite titanates
Magnetic ordering, orbital ordering, and resonant x-ray scattering in perovskite titanates
复制标题
钙钛矿钛酸盐中的磁有序、轨道有序和 X 射线共振散射
DOI：
10.1103/physrevb.65.064442
复制
发表时间：
2001
影响因子：
3.7
通讯作者：
S. Maekawa
中科院分区：
文献类型：
--
作者：
S. Ishihara;T. Hatakeyama;S. Maekawa
考虑到电子-电子相互作用和电子轨道的三重简并性，得到了钙钛矿型钛酸盐的有效哈密顿量。在有效哈密顿量的平均场近似下，研究了磁性有序相和轨道有序相。与双简并轨道的情况相反，铁磁相中的轨道态有很大的简并性。研究了由于晶格扭曲和自旋-轨道耦合引起的轨道简并的解除。导出了共振x射线散射截面的一般形式，并将其应用于最近的实验结果，研究了有序轨道中的自旋波色散关系。
The effective Hamiltonian for perovskite titanates is derived by taking into account the threefold degeneracy of ${t}_{2g}$ orbitals and the strong electron-electron interactions. The magnetic and orbital ordered phases are studied in the mean-field approximation applied to the effective Hamiltonian. A large degeneracy of the orbital states in the ferromagnetic phase is found in contrast to the case of the doubly degenerate ${e}_{g}$ orbitals. Lifting of this orbital degeneracy due to lattice distortions and spin-orbit coupling is examined. A general form for the scattering cross section of the resonant x-ray scattering is derived and is applied to the recent experimental results in ${\mathrm{YTiO}}_{3}.$ The spin wave dispersion relation in the orbital ordered ${\mathrm{YTiO}}_{3}$ is also studied.