On the field dependence of the vortex core size

TL;DR

This paper demonstrates that in clean high-$ppa$ type II superconductors, the vortex core size decreases with increasing magnetic field at low temperatures, aligning with experimental observations and providing a universal relation for different Fermi surface geometries.

Contribution

It introduces a theoretical analysis of the field dependence of vortex core size in clean superconductors, revealing a universal behavior at zero temperature.

Findings

Vortex core size decreases with increasing magnetic field.

Results are consistent for different Fermi surface geometries.

A universal function describes the core size dependence at T=0.

Abstract

We argue that in clean high-$\kappa$ type II superconductors, the low temperature vortex core size (defined as the coherence length $\xi$) in high fields should decrease with increasing applied field in qualitative agreement with experimental data. Calculations are done for the Fermi sphere and cylinder (with the field parallel to the cylinder axis). The results for clean materials at T=0 can be represented as $\xi(H)/\xi(H_{c2}) = U (H/H_{c2})$ with $U$ being an universal function.