Quasiparticle Thermal Conductivities in a Type-II Superconductor at High Magnetic Field

TL;DR

This paper calculates quasiparticle contributions to thermal conductivities in a high-field, low-temperature type-II superconductor, showing reductions from normal state values and matching experimental data for specific materials.

Contribution

It provides a theoretical framework for quasiparticle thermal conductivities in high-field superconductors, including numerical results that align with experimental observations.

Findings

Both conductivities decrease by $( ext{Gamma}/ ext{Delta})^2$ upon entering the superconducting state.

The theory accurately predicts thermal conductivities in LuNi2B2C.

Good agreement with recent experimental data.

Abstract

We present a calculation of the quasiparticle contribution to the longitudinal thermal conductivities as well as transverse (Hall) thermal conductivity of an extreme type-II superconductor in a high magnetic field and at low temperatures. In the limit of frequency and temperature approaching zero, both longitudinal and transverse conductivities upon entering the superconducting state undergo a reduction from their respective normal state values by the factor $(\Gamma /\Delta)^2$, which measures the size of the region at the Fermi surface containing gapless quasiparticle excitations. We use our theory to numerically compute the longitudinal transport coefficient in borocarbide and A-15 superconductors. The agreement with recent experimental data on LuNi_2B_2C is very good.