Radiation induced oscillating gap states of nonequilibrium two-dimensional superconductors

TL;DR

This paper investigates how infrared radiation affects a 2D superconductor coupled to a normal metal, revealing an oscillating gap phase and unusual Josephson currents due to nonequilibrium conditions.

Contribution

It introduces the concept of radiation-induced oscillating gap states in nonequilibrium 2D superconductors, highlighting a novel oscillation mechanism unrelated to the radiation frequency.

Findings

Identification of an oscillating gap phase driven by electron density asymmetry.

Prediction of an unusual alternating Josephson current in contact with another superconductor.

Analysis of phase transition conditions under infrared radiation influence.

Abstract

We study effects of infrared radiations on a two-dimensional BCS superconductor coupled with a normal metal substrate through a tunneling barrier. The phase transition conditions are analyzed by inspecting stability of the system against perturbations of pairing potentials. We find an oscillating gap phase with a frequency not directly related to the radiation frequency but resulting from the asymmetry of electron density of states of the system as well as the tunneling amplitude. When such a superconductor is in contact with another superconductor, it will give rise to an unusual alternating Josephson current.