Centre de Physique Théorique, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France.
Phys Rev Lett. 2011 Dec 23;107(26):266404. doi: 10.1103/PhysRevLett.107.266404. Epub 2011 Dec 22.
We discuss the notions of spin-orbital polarization and ordering in paramagnetic materials, and address their consequences in transition-metal oxides. Extending the combined density functional and dynamical mean field theory scheme to the case of materials with large spin-orbit interactions, we investigate the electronic excitations of the paramagnetic phases of Sr(2)IrO(4) and Sr(2)RhO(4). We show that the interplay of spin-orbit interactions, structural distortions and Coulomb interactions suppresses spin-orbital fluctuations. As a result, the room temperature phase of Sr(2)IrO(4) is a paramagnetic spin-orbitally ordered Mott insulator. In Sr(2)RhO(4), the effective spin-orbital degeneracy is reduced, but the material remains metallic, due to both, smaller spin-orbit and smaller Coulomb interactions. The corresponding spectra are in excellent agreement with photoemission data. Finally, we make predictions for the spectra of paramagnetic Sr(2)IrO(4).
我们讨论了顺磁材料中自旋轨道极化和有序的概念，并探讨了它们在过渡金属氧化物中的后果。通过将组合密度泛函和动力学平均场理论方案扩展到具有大自旋轨道相互作用的材料的情况，我们研究了 Sr(2)IrO(4)和 Sr(2)RhO(4)顺磁相的电子激发。我们表明，自旋轨道相互作用、结构畸变和库仑相互作用的相互作用抑制了自旋轨道涨落。结果，Sr(2)IrO(4)的室温相是顺磁自旋轨道有序的莫特绝缘体。在 Sr(2)RhO(4)中，由于较小的自旋轨道和较小的库仑相互作用，有效自旋轨道简并度降低，但材料仍保持金属性。相应的光谱与光电子数据非常吻合。最后，我们对顺磁 Sr(2)IrO(4)的光谱进行了预测。
