Negative resistance state in superconducting NbSe$_2$ induced by surface acoustic waves

TL;DR

This study demonstrates negative resistance in superconducting NbSe$_2$ thin films induced by surface acoustic waves, revealing a novel method to manipulate superconductivity through nonequilibrium effects.

Contribution

It introduces a new phenomenon of negative resistance in NbSe$_2$ under SAW irradiation and proposes a mechanism involving charge density wave soliton pairs.

Findings

Negative resistance observed in NbSe$_2$ under SAWs

Negative resistance increases with SAW power and decreases with temperature

Proposed mechanism involves charge density wave soliton pairs acting as a time-dependent capacitance

Abstract

We report a negative resistance, namely, a voltage drop along the opposite direction of a current flow, in the superconducting gap of NbSe$_2$ thin films under the irradiation of surface acoustic waves (SAWs). The amplitude of the negative resistance becomes larger by increasing the SAW power and decreasing temperature. As one possible scenario, we propose that soliton-antisoliton pairs in the charge density wave of NbSe$_2$ modulated by the SAW serve as a time-dependent capacitance in the superconducting state, leading to the dc negative resistance. The present experimental result would provide a previously unexplored way to examine nonequilibrium manipulation of the superconductivity.