标题： 自旋三重态配对不稳定性在二维排斥Hubbard模型中 显示英文标题

标题： Spin-triplet pairing instability in a two-dimensional repulsive Hubbard model

摘要： 寻找具有非常规配对对称性的超导性一直是强关联电子系统研究中的核心焦点。 在本工作中，我们报告了采用行列式量子蒙特卡罗方法对具有排斥相互作用的二维哈伯德模型中的自旋三重态配对进行数值精确研究。 该模型包括最近邻和第三近邻跃迁项，并保持自旋平衡。 通过调节费米子填充接近模型中的II型范霍夫奇点（vHs），我们数值研究了几种可能的配对通道在不同对称性下的序趋势。 我们的数值结果提供了清晰的证据，表明随着温度降低，自旋三重态$p$-波配对不稳定性出现，这由配对感生率的顶点贡献所揭示。 这种特征在弱到中等相互作用强度范围内随着相互作用强度的增加而变得更加明显。 我们进一步发现，在II型vHs附近，系统中的主要自旋-自旋关联是铁磁的，表明其与自旋三重态配对不稳定性密切相关。 我们的研究结果从无偏的数值角度提供了一种可靠的方法，在排斥哈伯德模型中实现自旋三重态$p$-波超流体。 显示英文摘要

摘要： The search for superconductivity with unconventional pairing symmetry has been a central focus in the study of strongly correlated electron systems. In this work, we report a numerically exact study of the spin-triplet pairing in a two-dimensional Hubbard model with repulsive interactions, employing Determinant Quantum Monte Carlo method. The model includes next-nearest-neighbor and third-nearest-neighbor hopping terms, and maintains spin balance. By tuning the fermion filling close to a type-II van Hove singularity (vHs) in the model, we numerically investigate the ordering tendencies of several possible pairing channels with different symmetries. Our numerical results provide clear evidence for the spin-triplet $p$-wave pairing instability approaching low temperatures, as revealed by the vertex contribution to the pairing susceptibility. This signature becomes increasingly pronounced as the interaction strength increases in the weak to intermediate regime. We further find that, near the type-II vHs, the dominant spin-spin correlations in the system are ferromagnetic, suggesting its close relation to the spin-triplet pairing instability. Our findings offer a reliable approach to realize the spin-triplet $p$-wave superfluidity in the repulsive Hubbard model, from an unbiased numerical perspective.