Surface reconstruction and energy gap of superconducting V3Si(001)

TL;DR

This study investigates the atomic-scale surface reconstruction of V3Si(001) and its superconducting energy gap using cryogenic STM, revealing stable gap width near impurities and evidence of Andreev reflections upon contact.

Contribution

It introduces a new surface reconstruction of V3Si(001) likely caused by carbon and explores its impact on the superconducting energy gap at the atomic level.

Findings

Gap width remains unchanged near carbon impurities and different surface sites.

Controlled contact induces Andreev reflections, indicating normal-metal–superconductor junctions.

Surface reconstruction influences spectroscopic signatures of the energy gap.

Abstract

A yet unknown surface reconstruction of V3Si(001), which is most likely induced by carbon, is used to investigate the quasi-particle energy gap at the atomic scale by a cryogenic scanning tunneling microscope. The width of the gap was virtually not altered at and close to carbon impurities, nor did it change at different sites of the reconstructed surface lattice. A remarkable modification of the spectroscopic signature of the gap was induced, however, upon moving the tip of the microscope into controlled contact with the superconductor. Spectroscopy of the resulting normal-metal -- superconductor junction indicated the presence of Andreev reflections.