Superconducting transition in Pb/Co nanocomposites: effect of Co volume fraction and external magnetic field

TL;DR

This study investigates how cobalt nanoparticle volume fraction and external magnetic fields influence the superconducting transition in Pb/Co nanocomposites, revealing effects on T$_{c}$ reduction and vortex formation.

Contribution

It provides detailed analysis of the impact of Co volume fraction and magnetic fields on superconductivity in Pb/Co nanocomposites, highlighting differences due to annealing.

Findings

Co nanoparticles induce spontaneous vortices below T$_{c}$

Annealed samples show different T$_{c}$ reduction due to coherence length differences

External magnetic field influences the superconducting transition

Abstract

Pb films embedded with homogeneously distributed cobalt (Co) nanoparticles (mean size 4.5 nm) have been prepared. Previous transport investigations have shown that Co particles induce spontaneous vortices below the superconducting transition temperature (T$_{c}$) in zero external magnetic field. In this paper we study in detail the influence of the Co volume franction and an external magnetic field on the superconducting transition in such composites. The large difference in T$_c$-reduction between the as-prepared and annealed samples can be attributed to the different superconducting coherence lengths and the resulting different diameters of the spontaneous vortices in these samples.