Field-angle resolved specific heat and thermal conductivity in the vortex phase of UPd_2Al_3

TL;DR

This study investigates the field-angle dependence of specific heat and thermal conductivity in UPd_2Al_3's vortex phase, using theoretical calculations to narrow down possible superconducting gap symmetries based on experimental data.

Contribution

The paper introduces a detailed numerical analysis of magnetothermal properties in UPd_2Al_3, constraining the superconducting gap symmetry by comparing calculations with experimental results.

Findings

Node lines in non-symmetry planes are excluded.

Field-angle oscillation amplitudes show nonmonotonic behavior due to scattering deviations.

Certain superconducting gap functions are strongly supported by the data.

Abstract

The field-angle dependent specific heat and thermal conductivity in the vortex phase of UPd_2Al_3 is studied using the Doppler shift approximation for the low energy quasiparticle excitations. We first give a concise presentation of the calculation procedure of magnetothermal properties with vortex and FS averages performed numerically. The comparison of calculated field-angle oscillations and the experimental results obtained previously leads to a strong reduction of the possible SC candidate states in UPd_2Al_3. The possible SC gap functions have node lines in hexagonal symmetry planes containing either the zone center or the AF zone boundary along c. Node lines in non-symmetry planes can be excluded. We also calculate the field and temperature dependence of field-angular oscillation amplitudes. We show that the observed nonmonotonic field dependence and sign reversal of the oscillation amplitude is due to small deviations from unitary scattering.