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.
Comment on 'Observation of Shapiro Steps in the Charge Density Wave State Induced by Strain on a Piezoelectric Substrate'
Kotelnikov Institute of Radioengineering and Electronics of RAS（俄罗斯科学院科尔尼尼科夫无线电电子学研究所）；Moscow Institute of Physics and Technology (National Research University)（莫斯科物理技术学院（国立研究型大学））
Electric-Field Breakdown of Absolute Negative Conductivity and Supersonic Streams in Two-Dimensional Electron Systems with Zero Resistance/Conductance States
Fundamental thermo-visco mechanical interactions governing the acoustic response of laser-excited nanoparticles
CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520 -IEMN- Institut d’Électronique de Microélectronique et de Nanotechnologie, University of Lille（法国国家科学研究中心、里尔中央理工学院、上法兰西理工大学、电子学与微纳米技术研究所）；Institute of Industrial Science, The University of Tokyo（东京大学工业科学研究所）；Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR5306（里昂第一大学、法国国家科学研究中心、光物质研究所）；Department of Mechanical, Chemical and Materials Engineering, Università degli Studi di Cagliari（卡利亚里大学机械、化学与材料工程系）
Modulating Surface Acoustic Wave Generation through Superconductivity
University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）；North Carolina State University（北卡罗来纳州立大学）；Argonne National Laboratory（阿贡国家实验室）；University of Central Florida（中佛罗里达大学）
