Comment on "Scaling of the quasiparticle spectrum for d-wave superconductors"

TL;DR

This paper critiques a recent proposed scaling law for d-wave superconductors, highlighting discrepancies in the crossover parameter and discussing the reasons for disagreement with prior findings.

Contribution

It clarifies the differences in the crossover parameter between two conflicting theories on d-wave superconductor properties.

Findings

Identifies the discrepancy in the crossover parameter

Analyzes the origin of disagreement between theories

Highlights the importance of the crossover parameter in superconductor behavior

Abstract

In a recent Letter Simon and Lee suggested a scaling law for thermodynamic and kinetic properties of superconductors with lines of gap nodes. However their crossover parameter between the bulk dominated regime and the vortex dominated regime is different from that found in our paper (N.B. Kopnin and G.E. Volovik, JETP Lett., {\bf 64}, 690 (1996); see also cond-mat/9702093). We discuss the origin of the disagreement.