论文标题
单频和多型超导体的$ t_c $的圆顶具有有限范围的互动
Domes of $T_c$ in single-band and multiband superconductors with finite-range attractive interactions
论文作者
论文摘要
在调谐载体密度或外部参数（例如压力或磁场）时，超导过渡温度的上升和下降在广泛的量子材料中被普遍存在。为了研究$ t_c $的此类圆顶，我们超越了原型的吸引人的哈伯德模型，并考虑通过瞬时，空间扩展，有吸引力的相互作用的电子晶格模型。通过数值求解均值场方程，并使用功能性重量化组方法超越平均场理论，我们发现对于特征交互范围$ \ ell $，存在$ t_c $ abour $ k_f \ ell \ el \！ \ sim \！ {\ Mathcal {O}}（1）$。对于多型系统，我们的平均场理论显示了Lifshitz过渡附近存在其他域。我们的结果在两个和三个维度上都存在，并且可以从费米表面和相互作用范围之间的几何关系中直观地理解。我们的模型可能与$ t_c $稀释的弱耦合超导体或工程冷原子系统的圆顶有关。
The rise and fall of the superconducting transition temperature $T_c$ upon tuning carrier density or external parameters, such as pressure or magnetic field, is ubiquitously observed in a wide range of quantum materials. In order to investigate such domes of $T_c$, we go beyond the prototypical attractive Hubbard model, and consider a lattice model of electrons coupled via instantaneous, spatially extended, attractive interactions. By numerically solving the mean-field equations, as well as going beyond mean field theory using a functional renormalization group approach, we find that for a characteristic interaction range $\ell$, there exists a dome in $T_c$ around $k_F \ell \! \sim \! {\mathcal{O}}(1)$. For multiband systems, our mean field theory shows the presence of additional domes in the vicinity of Lifshitz transitions. Our results hold in both two and three dimensions and can be intuitively understood from the geometric relation between the Fermi surface and the interaction range. Our model may be relevant for domes of $T_c$ in dilute weakly coupled superconductors or in engineered cold atom systems.
