论文标题
在复合超导体/金属双层系统中增强$ t _ {\ mathrm {c}} $：动态群集近似研究
Enhancing $T_{\mathrm{c}}$ in a composite superconductor/metal bilayer system: a dynamical cluster approximation study
论文作者
论文摘要
已经提出，非常规超导体的超导过渡温度$ t _ {\ mathrm {c}} $具有较大的配对量表，但可以通过将其耦合到金属来增强强相波动。但是，这种方法在不同的参数制度中的一般疗效仍然是一个悬而未决的问题。使用动态群集近似，我们在中间耦合方案中由有吸引力的哈伯德层组成的系统中研究了这个问题，在该系统中，有吸引力的库仑相互作用$ | u | $的大小比带宽$ w $略大，与非互操作的金属层杂交。我们发现，尽管随着层间跳跃的增加，超导过渡变得更加均值，但超导过渡温度$ t _ {\ mathrm {c}} $表现出对杂交$ t _ {\ perp} $的强度的非单调依赖性。这种行为是由相关层中有效配对相互作用的降低引起的，该相关层超过了由耦合到金属层引起的内在配对场易感性的增长。我们发现，对于复合系统，最大的$ t _ {\ mathrm {c}} $低于当前估计的隔离负$ u $ hubbard模型的最大值。
It has been proposed that the superconducting transition temperature $T_{\mathrm{c}}$ of an unconventional superconductor with a large pairing scale but strong phase fluctuations can be enhanced by coupling it to a metal. However, the general efficacy of this approach across different parameter regimes remains an open question. Using the dynamical cluster approximation, we study this question in a system composed of an attractive Hubbard layer in the intermediate coupling regime, where the magnitude of the attractive Coulomb interaction $|U|$ is slightly larger than the bandwidth $W$, hybridized with a noninteracting metallic layer. We find that while the superconducting transition becomes more mean-field-like with increasing interlayer hopping, the superconducting transition temperature $T_{\mathrm{c}}$ exhibits a nonmonotonic dependence on the strength of the hybridization $t_{\perp}$. This behavior arises from a reduction of the effective pairing interaction in the correlated layer that out-competes the growth in the intrinsic pair-field susceptibility induced by the coupling to the metallic layer. We find that the largest $T_{\mathrm{c}}$ inferred here for the composite system is below the maximum value currently estimated for the isolated negative-$U$ Hubbard model.
