Specific heat and low-lying excitations in the mixed state for a type II superconductor

TL;DR

This study uses self-consistent Eilenberger theory to analyze the low-temperature specific heat in the mixed state of a type II superconductor, revealing intrinsic T^2 contributions from vortex core effects.

Contribution

It identifies the origin of the T^2-term in specific heat as related to vortex density of states and core shrinking, providing new insights into vortex core electronic structure.

Findings

T^2-term in specific heat is intrinsic to vortex state.

Vortex core shrinking affects low-temperature thermodynamics.

Vortex core structure is richer than the normal core picture.

Abstract

Low temperature behavior of the electronic specific heat $C(T)$ in the mixed state is by the self-consistent calculation of the Eilenberger theory. In addition to $\gamma T$-term ($\gamma$ is a Sommerfeld coefficient), $C(T)$ has significant contribution of $T^2$-term intrinsic in the vortex state. We identify the origin of the $T^2$-term as (i) V-shape density of states in the vortex state and (ii) Kramer-Pesch effect of vortex core shrinking upon lowering $T$. These results both for full-gap and line node cases reveal that the vortex core is a richer electronic structure beyond the normal core picture.