Effect of thermal phase fluctuations on the superfluid density of two-dimensional superconducting films

TL;DR

This study investigates how thermal phase fluctuations influence the superfluid density in two-dimensional superconducting films, revealing a quantum crossover that suppresses classical phase fluctuations below a certain temperature.

Contribution

It provides high-precision measurements of complex conductivity in MoGe films, identifying a quantum crossover point affecting phase fluctuations.

Findings

Sharp drop in inverse sheet inductance at Tc

Classical phase fluctuations dominate just below Tc

Quantum crossover suppresses classical fluctuations below 0.94 Tco

Abstract

High precision measurements of the complex sheet conductivity of superconducting Mo77Ge23 thin films have been made from 0.4 K through Tc. A sharp drop in the inverse sheet inductance, 1/L(T), is observed at a temperature, Tc, which lies below the mean-field transition temperature, Tco. Just below Tc, the suppression of 1/L(T) below its mean-field value indicates that longitudinal phase fluctuations have nearly their full classical amplitude, but they disappear rapidly as T decreases. We argue that there is a quantum crossover at about 0.94 Tco, below which classical phase fluctuations are suppressed.