Measurements of microwave-enhanced superconductivity in aluminum strips

Abstract

Experiments investigating the influence of microwave irradiation on the critical current and the critical temperature for superconductivity in aluminum strips are presented. The microwave-induced enhancement of the critical current is shown to exist beyond the microwave-power level at which a discontinuous disappearance of superconductivity was previously reported. Microwave-enhanced critical temperatures are found up to 8% above the equilibrium value. It is essential to discern the role of microwave heating in these experiments. The measurements are extended to a lower temperature (40 mK) and to higher frequencies (36 GHz) than previously reported. It is discussed to what extent the observations fit qualitatively into microscopic models for enhanced superconductivity.