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arXiv 2301.07604cond-mat.supr-concond-mat.mes-hallcond-mat.mtrl-scicond-mat.soft
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薄膜超导电性的扩展解析BCS理论

Extended analytical BCS theory of superconductivity in thin films

Riccardo Travaglino, Alessio Zaccone

摘要:

我们提出了一个解析可解的BCS型超导理论,在良好的金属,这是限制在三个空间方向之一,如薄膜。得到了超导临界温度$T_c$随约束尺寸$L$变化的封闭式表达式,与实验数据定量吻合,没有可调参数。在增加的限制,交叉从一个球形费米表面,其中包含两个不断增长的空心球相对应的限制禁止的状态,到一个强烈变形的费米表面,预测。这种交叉代表了一种新的拓扑过渡,由禁闭驱动,属于两个不同的同伦类的两个费米表面之间。这种拓扑转变提供了一个机制的解释,通常观察到的非单调依赖性的$T_c$膜厚度的最大值,根据我们的理论,符合拓扑转变。

英文摘要:

We present an analytically solvable theory of BCS-type superconductivity in good metals which are confined along one of the three spatial directions, such as thin films. Closed-form expressions for the dependence of the superconducting critical temperature $T_c$ as a function of the confinement size $L$ are obtained, in quantitative agreement with experimental data with no adjustable parameters. Upon increasing the confinement, a crossover from a spherical Fermi surface, which contains two growing hollow spheres corresponding to states forbidden by confinement, to a strongly deformed Fermi surface, is predicted. This crossover represents a new topological transition, driven by confinement, between two Fermi surfaces belonging to two different homotopy classes. This topological transition provides a mechanistic explanation of the commonly observed non-monotonic dependence of $T_c$ upon film thickness with a maximum which, according to our theory, coincides with the topological transition.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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