Vortex Contribution to Specific Heat of Dirty $d$-Wave Superconductors: Breakdown of Scaling

TL;DR

This paper investigates how vortex contributions affect the specific heat of dirty d-wave superconductors, revealing a crossover from H^{1/2} to H log H behavior at low fields, which explains experimental discrepancies.

Contribution

It demonstrates that extended quasiparticle states dominate the vortex contribution in dirty d-wave superconductors, leading to a new low-field behavior and clarifying scaling limitations.

Findings

At low fields, the specific heat exhibits H log H behavior.

Extended quasiparticle states dominate in the dirty limit.

The crossover explains discrepancies in experimental measurements.

Abstract

We consider the problem of the vortex contribution to thermal properties of dirty d-wave superconductors. In the clean limit, the main contribution to the density of states in a d-wave superconductor arises from extended quasiparticle states which may be treated semiclassically, giving rise to a specific heat contribution \delta C(H)\sim H^{1/2}. We show that the extended states continue to dominate the dirty limit, but lead to a H \log H behavior at the lowest fields, H_{c1}\ltsim H\ll H_{c2}. This crossover may explain recent discrepancies in specific heat measurements at low temperatures and fields in the cuprate superconductors. We discuss the range of validity of recent predictions of scaling with H^{1/2}/T in real samples.