Low-Temperature Specific Heat of an Extreme-Type-II Superconductor at High Magnetic Fields

TL;DR

This study investigates the low-temperature specific heat of an extreme type-II superconductor under high magnetic fields, revealing a nonlinear field dependence consistent with experimental data for YNi₂B₂C.

Contribution

It applies a T-matrix approximation to model the quasiparticle contribution to specific heat, providing a theoretical framework matching experimental observations.

Findings

The electronic specific heat is linear in temperature with a field-dependent coefficient.

The calculated field dependence of the specific heat coefficient matches experimental data.

The theory is applicable for magnetic fields above approximately 15-20% of Hc2.

Abstract

We present a detailed study of the quasiparticle contribution to the low-temperature specific heat of an extreme type-II superconductor at high magnetic fields. Within a T-matrix approximation for the self-energies in the mixed state of a homogeneous superconductor, the electronic specific heat is a linear function of temperature with a linear-$T$ coefficient $\gamma_s(H)$ being a nonlinear function of magnetic field $H$. In the range of magnetic fields $H\agt (0.15-0.2)H_{c2}$ where our theory is applicable, the calculated $\gamma_s(H)$ closely resembles the experimental data for the borocarbide superconductor YNi$_2$B$_2$C.