AI 中文总结
研究双轨道哈伯德模型，发现轨道间项U'和$\tilde{t}$可增强超导关联，$\tilde{t}=0$时U'屏蔽U使超导穹顶偏移，$\tilde{t}$的引入因平带与宽带共存进一步提升超导关联。
AI 中文摘要
我们借助量子蒙特卡罗技术，基于Jastrow-Slater波函数的变分假设，研究了一个最小双轨道哈伯德模型，该模型包含轨道内与轨道间的最近邻跃迁$t$和$\tilde{t}$，以及轨道内与轨道间的密度-密度相互作用$U$和$U'$。为聚焦于超导电性的电子机制，我们将变分假设限定为具有明确配对振幅的均匀非磁性态，并计算配对关联随填充率及模型参数的变化。在$U/t=10$时，轨道间项$U'$和$\tilde{t}$的存在使超导关联大幅增强。当$\tilde{t}=0$时，有限的$U'$可有效屏蔽轨道内排斥$U$，导致超导穹顶发生偏移。因此，与单轨道基准相比，轨道间排斥使电子配对显著增加。此外，引入有限的$\tilde{t}$可进一步提升超导关联，该效应由电子结构中平带与宽带共存所驱动。
英文摘要
We investigate a minimal two-orbital Hubbard model with intra- and inter-orbital nearest-neighbor hopping $t$ and $\tilde{t}$, as well as intra- and inter-orbital density-density interactions $U$ and $U'$ by means of variational ansätze based on Jastrow-Slater wave functions within quantum Monte Carlo techniques. To focus on the electronic mechanisms of superconductivity, we restrict the variational ansätze to uniform nonmagnetic states with an explicit pairing amplitude and compute the pairing correlations as a function of filling and model parameters. At $U/t=10$, superconducting correlations are highly enhanced by the presence of inter-orbital terms, $U'$ and $\tilde{t}$. For $\tilde{t}=0$, a finite value of $U'$ effectively screens the intra-orbital repulsion $U$, producing a shift in the superconducting dome. Consequently, inter-orbital repulsion yields a sizable increase in electron pairing compared to the single-orbital baseline. Furthermore, introducing a finite $\tilde{t}$ provides an additional boost to superconducting correlations, an effect driven by the simultaneous presence of flat and broad bands in the electronic structure.
