Photogalvanic transport in fluctuating Ising superconductors

TL;DR

This paper investigates the photogalvanic effect in 2D noncentrosymmetric Ising superconductors, highlighting contributions from normal electron currents and fluctuating Cooper pairs near the transition temperature, influenced by valley degeneracy lifting.

Contribution

It introduces a theoretical framework combining Boltzmann and Ginzburg-Landau equations to analyze photogalvanic effects in fluctuating Ising superconductors, considering valley effects and magnetic field influence.

Findings

Identifies two contributions to the photogalvanic effect: normal state and fluctuating Cooper pairs.

Shows how a weak magnetic field lifts valley degeneracy, affecting the photogalvanic response.

Provides a theoretical model applicable to transition metal dichalcogenide Ising superconductors.

Abstract

In a two-dimensional noncentrosymmetric Ising superconductor in the fluctuating regime under the action of a uniform external electromagnetic field there emerge two contributions to the photogalvanic effect due to the trigonal warping of the valleys. The first contribution stems from the current of the electron gas in its normal state, while the second contribution is of Aslamazov-Larkin nature: it originates from the presence of fluctuating Cooper pairs when the ambient temperature approaches (from above) the temperature of superconducting transition in the sample. The way to lift the valley degeneracy is the application of a weak out-of-plane external magnetic field producing a Zeeman effect. The Boltzmann equations approach for the electron gas in the normal state and the time-dependent Ginzburg-Landau equations for the fluctuating Cooper pairs allow for the study of the photogalvanic current in two-dimensional transition metal dichalcogenide Ising superconductors.