Point-Contact Spectroscopy in MgB_2: from Fundamental Physics to Thin-Film Characterization

TL;DR

This paper discusses how point-contact spectroscopy (PCS) can be used both to study fundamental properties of MgB_2 superconductors and to assess and optimize thin-film quality for electronic applications.

Contribution

It demonstrates the dual use of PCS as a fundamental physics probe and a non-destructive diagnostic tool for MgB_2 thin films.

Findings

Temperature dependence of superconducting gaps measured by PCS

Magnetic field effects on gap amplitudes observed

PCS provides surface property insights for film optimization

Abstract

In this paper we highlight the advantages of using point-contact spectroscopy (PCS) in multigap superconductors like MgB_2, both as a fundamental research tool and as a non-destructive diagnostic technique for the optimization of thin-film characteristics. We first present some results of crucial fundamental interest obtained by directional PCS in MgB_2 single crystals, for example the temperature dependence of the gaps and of the critical fields and the effect of a magnetic field on the gap amplitudes. Then, we show how PCS can provide useful information about the surface properties of MgB_2 thin films (e.g. Tc, gap amplitude(s), clean or dirty-limit conditions) in view of their optimization for the fabrication of tunnel and Josephson junctions for applications in superconducting electronics.