Investigations of the Core Structure of Magnetic Vortices in Type-II Superconductors by muSR

TL;DR

This paper uses muSR to study the core structure of magnetic vortices in type-II superconductors, revealing how vortex size depends on temperature, magnetic field, and the superconducting gap, with implications for understanding high-temperature superconductivity.

Contribution

It demonstrates that muSR measurements of vortex core size are highly sensitive to the superconducting gap structure and Fermi surface symmetry, providing new insights into vortex behavior in various superconductors.

Findings

Vortex core size varies with temperature and magnetic field.

Large vortex cores in YBa2Cu3O6.95 are linked to CuO chain superconductivity.

Vortex core size is influenced by the superconducting energy gap and Fermi surface symmetry.

Abstract

Muon spin rotation (muSR) has emerged as the leading experimental probe of the effective size of magnetic vortices in type-II superconductors. muSR data on several different classes of type-II superconductors shows that the inner structure of a vortex can depend quite strongly on temperature and the strength of the external magnetic field. In this paper it is shown that these behaviours are related to the quasiparticle excitation spectrum both inside and outside of the vortex cores. Here we establish that the vortex-core size determined by muSR is particularly sensitive to the nature of the superconducting energy gap(s) and the symmetry of the Fermi surface. A survey of results for different superconductors arrives at the conclusion that the large vortex-core size observed by muSR in YBa2Cu3O6.95 is due to CuO chain superconductivity.