Proximity-Induced Superconductivity in a Topological Crystalline Insulator

TL;DR

This study demonstrates proximity-induced superconductivity in a topological crystalline insulator (SnTe) using heterostructure growth and surface spectroscopy, opening avenues for exploring topological phases protected by crystalline symmetries.

Contribution

It introduces a novel heterostructure approach to induce and observe superconductivity on SnTe surfaces, enabling atomic-scale studies of topological phenomena.

Findings

Spectral gap observed on SnTe surface indicating superconductivity

Superconducting gap depends on temperature and magnetic field

Heterostructure effectively bridges lattice mismatch for surface studies

Abstract

Superconducting topological crystalline insulators (TCI) are predicted to host new topological phases protected by crystalline symmetries, but available materials are insufficiently suitable for surface studies. To induce superconductivity at the surface of a prototypical TCI SnTe, we use molecular beam epitaxy to grow a heterostructure of SnTe and a high-Tc superconductor Fe(Te,Se), utilizing a 'buffer' layer to bridge the large lattice mismatch between SnTe and Fe(Te,Se). Using low-temperature scanning tunneling microscopy and spectroscopy, we measure a prominent spectral gap on the surface of SnTe, and demonstrate its superconducting origin by its dependence on temperature and magnetic field. Our work provides a new platform for atomic-scale investigations of emergent topological phenomena in superconducting TCIs.