Local density of state fluctuations in 2D superconductor as a probe of quantum diffusion

TL;DR

This study investigates how local density of states fluctuations in a 2D superconductor reveal information about quantum diffusion and scattering processes, using an epitaxial lead monolayer as a model system.

Contribution

It demonstrates that mesoscopic LDOS fluctuations can serve as a local probe for elastic and inelastic scattering rates in 2D superconductors, validated through analytical and numerical methods.

Findings

LDOS fluctuations correlate with scattering rates

Spectral energy gap fluctuations reflect disorder effects

Mesoscopic fluctuations can be used to probe quantum diffusion

Abstract

The interplay of superconductivity and disorder generates a wealth of complex phenomena. In particular, the peculiar structure of diffusive electronic wavefunctions is predicted to increase the superconducting critical temperature in some range of disorder. In this work, we use an epitaxial monolayer of lead showing a simple band structure and homogenous structural disorder as a model system of a 2D superconductor in the weak-antilocalization regime. Then, we perform an extensive study of the emergent fluctuations of local density of states (LDOS) and spectral energy gap in this material and compare them with both analytical results and numerical solution of the attractive Hubbard model. We show that mesoscopic LDOS fluctuations allow to probe locally both the elastic and inelastic scattering rates which are notoriously difficult to measure in transport measurements.