Field dependence of the zero energy density of states around vortices in an anisotropic gap superconductor

TL;DR

This paper theoretically investigates how the magnetic field dependence of the zero-energy density of states in an anisotropic gap superconductor reveals information about the gap topology, aiding in distinguishing nodal and anisotropic full gaps.

Contribution

It provides a microscopic quasi-classical evaluation of the Sommerfeld coefficient's dependence on magnetic induction, linking it to gap anisotropy and topology.

Findings

Linear relation of γ(B) with B reflects gap anisotropy.

Slope of γ(B) indicates nodal versus full gap structure.

Method allows estimation of gap anisotropy magnitude.

Abstract

It is shown theoretically that the Sommerfeld coefficient $\gamma(B)$ in the mixed state contains useful information on the gap topology in a superconductor. We accurately evaluate $\gamma(B)$ against magnetic induction $B$ by using microscopic quasi-classical theory. The linear portion in {$\gamma(\propto B)$} relative to $B_{\rm c2}$ and its slope in low field faithfully corresponds to the gap anisotropy, so that we can distinguish the nodal gap and the anisotropic full gap, and estimate the magnitude of the gap anisotropy.