Quasiparticle Density of States of Clean and Dirty s-Wave Superconductors in the Vortex State

TL;DR

This study investigates the quasiparticle density of states in the vortex state of clean and dirty s-wave superconductors using specific heat measurements, revealing different magnetic field dependencies linked to vortex core behavior.

Contribution

It provides experimental evidence of how the quasiparticle DOS varies with magnetic field in clean versus dirty superconductors, highlighting vortex core dynamics.

Findings

DOS per vortex depends on H in clean superconductors

DOS per vortex is H-independent in dirty superconductors

Vortex core radius shrinks with increasing magnetic field

Abstract

The quasiparticle density of states (DOS) in the vortex state has been probed by specific heat measurements under magnetic fields (H) for clean and dirty s-wave superconductors, Y(Ni1-xPtx)2B2C and Nb1-xTaxSe2. We find that the quasiparticle DOS per vortex is appreciably H-dependent in the clean-limit superconductors, while it is H-independent in the dirty superconductors as expected from a conventional rigid normal electron core picture. We discuss possible origins for our observations in terms of the shrinking of the vortex core radius with increasing H.