Pairing symmetry in a two-orbital Hubbard model on a square lattice
Pairing symmetry in a two-orbital Hubbard model on a square lattice
复制标题
DOI：
10.1103/physrevb.75.224509
复制
发表时间：
2007-06-01
影响因子：
3.7
通讯作者：
Kubo, Katsunori
中科院分区：
文献类型：
--
作者：
Kubo, Katsunori
利用涨落交换近似研究了正方晶格上双轨道Hubbard模型的超导电性。在本模型中，两个轨道的对称性被假定为s轨道的对称性。然后，我们发现当Hund规则耦合较大时，会出现s波自旋三重态轨道反对称态和p波自旋单重态轨道反对称态。这些状态在单轨道模型中被禁止，但允许多轨道系统。我们还讨论了除轨道对称性外与双轨道Hubbard模型等价的其他模型中的对对称性。最后，我们表明，配对状态与一个有限的总动量，即使没有磁场，在一个系统中有两个费米面是可能的。
We investigate superconductivity in a two-orbital Hubbard model on a square lattice by applying fluctuation exchange approximation. In the present model, the symmetry of the two orbitals are assumed to be that of an s orbital. Then, we find that an s-wave spin-triplet orbital-antisymmetric state and a p-wave spin-singlet orbital-antisymmetric state appear when Hund's rule coupling is large. These states are prohibited in a single-orbital model within states with even frequency dependence, but allowed for multiorbital systems. We also discuss pairing symmetry in other models which are equivalent to the two-orbital Hubbard model except for symmetry of orbitals. Finally, we show that pairing states with a finite total momentum, even without a magnetic field, are possible in a system with two Fermi surfaces.