标题： Eliashberg理论对超导薄膜在直流电场下的临界电流预测 显示英文标题

标题： Eliashberg theory prediction of critical currents in superconducting thin films under DC electric fields

摘要： 超导金属薄膜作为超电流门控可调晶体管，在未来量子电子器件中有相当大的潜力。 尽管进行了大量研究，但全面的微观定量机制来解释薄膜中对超电流的控制或抑制仍然难以捉摸。 以NbN为例，这是一种典型材料，从一个现象学假设出发，该假设将临界电场与破坏库珀对所需的动能参数联系起来，我们在无自由参数的情况下使用Eliashberg理论在脏极限下提供了临界电流的定量分析。 确定了临界动能值，对应于薄膜中可能流动的最大超电流。 超电流密度随库珀对动能变化的峰值来源于由于动能增加导致的超电流增加与当动能变得足够大时的去配对效应之间的相互作用。 随后利用对库珀对动能的临界值来估计外部电场的临界值，以抑制样品中的超导性。 这种估计与实验观察结果无参数一致。 虽然无序降低了门控效应对临界电流温度依赖性的降低，同时增加了抑制超导性所需的未屏蔽临界电场。 这使得提出了控制和减少超导电子器件中抑制超导性所需的临界场值的方法。 显示英文摘要

摘要： Superconducting thin metallic films, functioning as supercurrent gate-tunable transistors, have considerable potential for future quantum electronic devices. Despite extensive research, a comprehensive microscopic quantitative mechanism that elucidates the control or suppression of supercurrents in thin films remains elusive. Focusing on NbN, a prototypical material, and starting from a phenomenological ansatz that links the critical electric field with the kinetic energy parameter needed to break Cooper pairs, we provide a quantitative analysis of the critical current using Eliashberg theory in the dirty limit without adjustable parameters. The critical kinetic energy value is identified, corresponding to the maximum supercurrent that can flow in the thin film. The peak in supercurrent density as a function of the Cooper pairs' kinetic energy arises from the interplay between the increase in supercurrent due to increased kinetic energy and the depairing effect when the kinetic energy becomes sufficiently large. The critical value of the pair's kinetic energy is subsequently employed to estimate the critical value of an external electric field required to suppress superconductivity in the sample. This estimation is in parameter-free agreement with the experimental observations. Although the disorder reduces the temperature dependence of the gating effect on the critical current, at the same time, it increases the unscreened critical electric field needed to suppress superconductivity. This enables the proposal of methods to control and reduce the critical field value necessary to suppress superconductivity in superconducting electronics.