论文标题
拓扑声子介导的超导性理论
Theory of Superconductivity Mediated by Topological Phonons
论文作者
论文摘要
拓扑音调绝缘子是语音系统中三维量子旋转霍尔绝缘子的对应物，因此，它们的拓扑表面的特征是由于散装与实体的对应关系而导致的狄拉克锥形无间隙边缘状态。我们为这些材料中可能的超导阶段提出了一个理论框架，在这些材料中，电子之间的有吸引力的相互作用是由拓扑声子在非平凡边界模式下介导的。在BCS限制内，我们开发了一个自一致的两波段差距方程，其解决方案表明，超导临界温度相对于类似Kramers的点的语音频率具有非单调的行为。这种出色的行为是由共振产生的，这种共振发生在拓扑表面上的电子和声子具有相同的能量时发生：这有效地增加了电子量子的相互作用，因此库珀对结合能，从而建立了超导阶段的最佳条件。有了这种机制，$ t_ {c} $可以超过两个因子，而最大增强功能则在退化的语音平面限制中发生。
Topological phononic insulators are the counterpart of three-dimensional quantum spin Hall insulators in phononic systems and, as such, their topological surfaces are characterized by Dirac cone-shaped gapless edge states arising as a consequence of a bulk-boundary correspondence. We propose a theoretical framework for the possible superconducting phase in these materials, where the attractive interaction between electrons is mediated by topological phonons in nontrivial boundary modes. Within the BCS limit, we develop a self-consistent two-band gap equation, whose solutions show that the superconducting critical temperature has a non-monotonic behaviour with respect to the phononic frequency in the Kramers-like point. This remarkable behaviour is produced by a resonance, that occurs when electrons and phonons on the topological surfaces have the same energy: this effectively increases the electron-phonon interaction and hence the Cooper pair binding energy, thus establishing an optimal condition for the superconducting phase. With this mechanism, the $T_{c}$ can be increased by well over a factor two, and the maximum enhancement occurs in the degenerate phononic flat-band limit.
