Quasiparticle transport in the vortex state of YBa_2Cu_3O_6.9

TL;DR

This study investigates how vortices affect quasiparticle transport in YBa_2Cu_3O_6.9 superconductors by measuring thermal conductivity under magnetic fields, revealing insights into quasiparticle states and scattering mechanisms.

Contribution

It provides experimental evidence on vortex influence on quasiparticles and compares results with theoretical models for d-wave superconductors, advancing understanding of impurity and vortex scattering.

Findings

Residual linear term increases with magnetic field

Good agreement with d-wave superconductor calculations

Quantitative measure of the gap near the nodes

Abstract

The effect of vortices on quasiparticle transport in cuprate superconductors was investigated by measuring the low temperature thermal conductivity of YBa_2Cu_3O_6.9 in magnetic fields up to 8 T. The residual linear term (as T \to 0) is found to increase with field, directly reflecting the occupation of extended quasiparticle states. A study for different Zn impurity concentrations reveals a good agreement with recent calculations for a d-wave superconductor, thereby shedding light on the nature of scattering by both impurities and vortices. It also provides a quantitative measure of the gap near the nodes.