The question of whether spatially inhomogeneous hopping in the two dimensional Hubbard model can lead to enhancement of superconductivity has been tackled by a number of authors in the context of the checkerboard Hubbard model (CHM). We address the effects of disorder on superconducting properties of the CHM by using exact diagonalization calculations for both potential and hopping disorder. We characterize the superconducting tendencies of the model by focusing on the pair binding energy, the spin gap, and d-wave pairing order parameter. We find that superconducting tendencies, particularly the pair binding energy, are more robust to disorder when there is inhomogeneous hopping than for the uniform Hubbard model. We also study all possible staggered potentials for an eight site CHM cluster and relate the behaviour of these configurations to the disordered system.
Pairing Tendencies in a Two-orbital Hubbard Model in One Dimension
最近在梯形化合物BaFe $_2$ S $_3$中发现的高压超导电性为铁基超导体的准一维几何结构研究开辟了新的领域。本文利用密度矩阵重整化群方法研究了一维链中的双轨道哈伯德模型。我们的主要结果是在中间Hubbard $U$排斥和鲁棒Hund耦合$J_H/U=0.25$下存在空穴结合趋势。无论是在弱耦合还是在非常强的耦合中，结合都不会发生。在接近半填充时占主导地位的对-对关联，或与电荷和自旋关联通道具有类似强度的对-对关联，涉及自旋单线态的空穴对算符，使用最近邻位点，并为每个空穴使用不同的轨道。Hund耦合强度，存在强大的磁矩，以及它们之间的反铁磁相关性是很重要的约束力的倾向，在这里找到。
The pseudogap regime of the cuprate high-temperature superconductors is characterized by a variety of competing orders, the nature of which are still widely debated. Recent experiments have provided evidence for electron nematic order, in which the electron fluid breaks rotational symmetry while preserving translational invariance. Raman spectroscopy, with its ability to symmetry resolve low energy excitations, is a unique tool that can be used to assess nematic fluctuations and nematic ordering tendencies. Here, we compare results from determinant quantum Monte Carlo simulations of the Hubbar…
