Electron-electron relaxation in two-dimensional impure superconductors

TL;DR

This paper investigates electron-electron relaxation mechanisms in impure two-dimensional superconductors, revealing temperature-dependent behaviors of relaxation rates and implications for superconducting detector design.

Contribution

It provides a comprehensive analysis of all electron-electron interaction channels in 2D superconductors, including effects of fluctuations and inter-layer Coulomb interactions.

Findings

Recombination relaxation rate shows double exponential temperature dependence at low temperatures.

Scattering relaxation rate follows a power law temperature dependence due to phase modes.

Inter-layer Coulomb interaction increases the recombination relaxation rate in bilayer systems.

Abstract

The electron-electron relaxation in impure two-dimensional superconductors is studied. All channels of the electron-electron interaction classified in the Nambu representation are taken into account. It is shown that the recombination relaxation rate originates from quasipartical processes associated with fluctuations of the electron density and the phase of the order parameter. At low temperatures the recombination relaxation rate has a double exponential temperature dependence. The scattering relaxation rate at low temperatures has a power law temperature dependence due to contributions from gapless collective excitations, the phase modes. Two-layer superconductor-normal metal system is also considered. It is shown that the recombination relaxation rate in the superconducting layer has a single exponential factor at low temperatures in comparison with a one layer superconducting system. This increase in the recombination relaxation rate originates from the inter-layer Coulomb interaction and may be used in constructing of superconducting radiation detectors.