论文标题
弱耦合极限以埃里亚斯贝格超导体的电导率和核磁共振松弛速率
Electrical conductivity and nuclear magnetic resonance relaxation rate of Eliashberg superconductors in the weak-coupling limit
论文作者
论文摘要
电导率是超导体中重要的运输响应，可以观察到动态相互作用的明确特征。本文中的主要兴趣是研究弱耦合Eliashberg理论（ETH）中电子波相互作用的特征，并注意Bardeen-Cooper-Schrieffer（BCS）理论的区别。对弱耦合ETH的最新分析表明，尽管BCS结果进行了修改，但某些无量纲比率仍一致。在这里，我们表明，BCS理论和伦理学的电导率在根本上有所不同，后者具有抑制差异的假想间隙成分。我们专注于肮脏的极限，对于BCS理论和ETH，我们都会为真实电导率的低频极限提供表达。对于ETH而言，根据频率的相对大小和间隙的假想部分，需要考虑两个限制。在零频率相同的情况下，我们得出了核磁共振松弛率的分析表达。我们对电导率的分析补充了对Meissner响应的先前研究，并提供了对弱耦合ETH的彻底理解。
Electrical conductivity is an important transport response in superconductors, enabling clear signatures of dynamical interactions to be observed. Of primary interest in this paper is to study characteristics of the electron-phonon interaction in weak-coupling Eliashberg theory (Eth), and to note the distinctions with Bardeen-Cooper-Schrieffer (BCS) theory. Recent analysis of weak-coupling Eth has shown that while there are modifications from the BCS results, certain dimensionless ratios are in agreement. Here we show that the conductivities in BCS theory and Eth fundamentally differ, with the latter having an imaginary gap component that damps a divergence. We focus on the dirty limit, and for both BCS theory and Eth we derive expressions for the low-frequency limit of the real conductivity. For Eth specifically, there are two limits to consider, depending on the relative size of the frequency and the imaginary part of the gap. In the case of identically zero frequency, we derive an analytical expression for the nuclear magnetic resonance relaxation rate. Our analysis of the conductivity complements the previous study of the Meissner response and provides a thorough understanding of weak-coupling Eth.
