Electronic Structures, Magnetism, and Phonon Spectra in the Metallic Cubic Perovskite BaOsO3
arXiv:1405.4591 · doi:10.1103/PhysRevB.90.045120
Abstract
Using ab initio calculations, we have investigated a cubic perovskite BaOsO3 and a few related compounds that have been synthesized recently and formally have a metallic d^4 configuration. In BaOsO3, which shows obvious 3-dimensional fermiology, a nonmagnetism is induced by a large spin-orbit coupling (SOC), which is precisely equal to an exchange splitting ~0.4 eV of the manifold. However, the inclusion of on-site Coulomb repulsion as small as ~1.2 eV, only 1/3 of the bandwidth, leads to the emergence of a spin-ordered moment, indicating that this system is on the verge of magnetism. In contrast to BaOsO3, our calculations suggest that the ground state of an orthorhombic CaOsO3 is a magnetically ordered state due to the reduction of the strength of SOC (about a half of that of BaOsO3) driven by the structure distortion, although the magnetization energy is only a few tenths of meV. Furthermore, in the cubic BaOsO3 and BaRuO3, our full-phonon calculations show several unstable modes, requiring further research.
6 pages, 6 figures
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