Disorder-induced suppression of superconductivity in the Si(111)-($\sqrt{7}\times\sqrt{3}$)-In surface: Scanning tunneling microscopy study

TL;DR

This study investigates how disorder affects superconductivity on a Si(111)-($\

Contribution

It provides direct STM evidence showing disorder suppresses superconductivity in a 2D surface system, with analysis of local spectra and vortices.

Findings

Superconductivity persists in less disordered regions.

Superconductivity is suppressed in highly disordered regions.

Zero-bias anomalies relate to reduced transition temperature.

Abstract

The critical effect of disorder on the two-dimensional (2D) surface superconductor Si(111)-($\sqrt{7}\times\sqrt{3}$)-In is clarified by comparing two regions with different degrees of disorder. Low-temperature scanning tunneling microscopy measurements reveal that superconductivity is retained in the less disordered region, judging from the characteristic differential conductance ($dI/dV$) spectra and from the formation of vortices under magnetic fields. In striking contrast, the absence of those features in the highly disordered region shows that superconductivity is strongly suppressed there. Analysis of observed zero-bias anomalies in $dI/dV$ spectra allows us to estimate the reduction in the transition temperature $T_{\rm c}$, which explains the fate of superconductivity in each region.