用Hartree-Fock和Heisenberg近似下的五轨道模型研究铁超导体中的磁相互作用
Magnetic interactions in iron superconductors studied with a five-orbital model within the Hartree-Fock and Heisenberg approximations
摘要：
我们分析了在哈特里-福克和海森堡近似下处理的铁超导体五轨道模型的磁相互作用。我们发现交换常数与Fe-As-Fe夹角、电荷和轨道填充密切相关。在定域图中，对于中间Hund耦合J_H，存在柱状有序.在较小的J_H，一个不寻常的轨道重组稳定棋盘秩序。铁磁性出现在大J_H处。铁磁相关性的增强与电子掺杂，而大孔掺杂稳定棋盘式反铁磁性，解释的变化后，由Co或Mn取代Fe的磁相互作用。对于中等和大的U值，Hartree-Fock显示了类似的结果，强耦合，虽然用双条纹相代替铁磁性。流动增强了柱状有序的稳定性。这两种方法的比较揭示了强耦合物理是决定性的相图的金属区域。
英文摘要：
We have analyzed the magnetic interactions of a five orbital model for iron superconductors treated both within Hartree-Fock and Heisenberg approximations. We have found that the exchange constants depend non-trivially on the Fe-As-Fe angle and on the charge and orbital filling. Within the localized picture, columnar ordering is found for intermediate Hund's coupling J_H. At smaller J_H, an unusual orbital reorganization stabilizes checkerboard ordering. Ferromagnetism appears at large J_H. Ferromagnetic correlations are enhanced with electron doping while large hole doping stabilizes checkerboard antiferromagnetism, explaining the change in magnetic interactions upon substitution of Fe by Co or Mn. For intermediate and large values of U, Hartree-Fock shows similar results as strong coupling though with a double stripe phase instead of ferromagnetism. Itinerancy enhances the stability of the columnar ordering. Comparison of the two approaches reveals a metallic region of the phase diagram where strong coupling physics is determinant.
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