Molecular beam epitaxy of superconducting Sn$_{1-x}$In$_x$Te thin films

TL;DR

This study systematically optimizes molecular beam epitaxy growth conditions for Sn$_{1-x}$In$_x$Te thin films, achieving high In substitution levels and superconducting transition temperatures, enabling future topological superconductivity research.

Contribution

It demonstrates the successful growth of high-quality Sn$_{1-x}$In$_x$Te films with enhanced In content and superconductivity beyond bulk limits using MBE.

Findings

Maximum $T_c$ of 4.20 K at $x$=0.55

In content $x$=0.66 achieved beyond bulk solubility limit

Superconducting $T_c$ shows dome-shaped dependence on In content

Abstract

We report a systematic study on the growth conditions of Sn$_{1-x}$In$_x$Te thin films by molecular beam epitaxy for maximization of superconducting transition temperature $T_\mathrm{c}$. Careful tuning of the flux ratios of Sn, In, and Te enables us to find an optimum condition for substituting rich In content ($x$ = 0.66) into Sn site in a single phase of Sn$_{1-x}$In$_x$Te beyond the bulk solubility limit at ambient pressure ($x$ = 0.5). $T_\mathrm{c}$ shows a dome-shaped dependence on In content $x$ with the highest $T_\mathrm{c}$ = 4.20 K at $x$ = 0.55, being consistent to that reported for bulk crystals. The well-regulated Sn$_{1-x}$In$_x$Te films can be a useful platform to study possible topological superconductivity by integrating them into the state-of-the-art junctions and/or proximity-coupled devices.