Macroscopic Superconducting Current through a Silicon Surface Reconstruction with Indium Adatoms: Si(111)-(R7$\times$R3)-In

TL;DR

This study demonstrates macroscopic superconducting currents on a silicon surface with indium adatoms, showing a transition below 2.8 K and indicating atomic steps act as Josephson junctions, revealing potential for surface-based superconducting devices.

Contribution

First observation of macroscopic superconducting current on a silicon surface with indium adatoms, highlighting atomic steps as Josephson junctions and characterizing surface superconductivity.

Findings

Superconducting transition below 2.8 K with zero resistance.

High 2D critical current density of 1.8 A/m at 1.8 K.

Atomic steps act as strongly coupled Josephson junctions.

Abstract

Macroscopic and robust supercurrents are observed by direct electron transport measurements on a silicon surface reconstruction with In adatoms (Si(111)-(R7xR3)-In). The superconducting transition manifests itself as an emergence of the zero resistance state below 2.8 K. $I-V$ characteristics exhibit sharp and hysteretic switching between superconducting and normal states with well-defined critical and retrapping currents. The two-dimensional (2D) critical current density $J_\mathrm{2D,c}$ is estimated to be as high as $1.8 \ \mathrm{A/m}$ at 1.8 K. The temperature dependence of $J_\mathrm{2D,c}$ indicates that the surface atomic steps play the role of strongly coupled Josephson junctions.