Tailoring Superconductivity with Two-Level Systems

TL;DR

This paper explores how two-level systems (TLSs) influence superconductivity, demonstrating that TLSs can be used to control the critical temperature and gap in materials like aluminium, opening new avenues for material property engineering.

Contribution

It provides a quantitative analysis of TLS effects on superconductivity, revealing how defect density and frequency can be tuned to modify superconducting properties.

Findings

TLSs can either enhance or suppress superconductivity.

Surface density and frequency of TLSs determine their impact.

Quantitative description for aluminium thin films.

Abstract

We investigate the impact of two-level systems (TLSs) on superconductivity, treating them as soft modes localised in real space. We show that these defects can either enhance or suppress the superconducting critical temperature, depending on their surface density and average frequency. Using thin-film aluminium as a case study, we quantitatively describe how TLSs modify both the critical temperature and the zero-temperature superconducting gap. Our results thus highlight new opportunities for tailoring material properties through TLS engineering.