Dissipationless BCS Dynamics with Large Branch Imbalance

TL;DR

This paper investigates the short-time dynamics of a superconductor with large branch imbalance after an instability, using collisionless methods to understand the behavior beyond the gap suppression point.

Contribution

It introduces a collisionless approach to analyze the immediate post-instability dynamics in imbalanced BCS superconductors.

Findings

Identifies the short-time evolution following the instability.

Provides a framework for analyzing dynamics beyond the gap suppression.

Highlights the role of collisionless regimes in superconductor behavior.

Abstract

In many situations a BCS-type superconductor will develop an imbalance between the populations of the holelike and electronlike spectral branches. This imbalance suppresses the gap. It has been noted by Gal'perin et al. [Sov. Phys. JETP 54, 1126 (1981)] that at large imbalance, when the gap is substantially suppressed, an instability develops. The analytic treatment of the system beyond the instability point is complicated by the fact that the Boltzmann approach breaks down. We study the short-time behavior following the instability, in the collisionless regime, using methods developed by Yuzbashyan et al. [J. Phys. A 38, 7831 (2005); Phys. Rev. B 72, 220503(R) (2005)].