Anisotropic inelastic scattering and its interplay with superconductivity in URu$_{2}$Si$_{2}$

TL;DR

This study reveals unusual anisotropic inelastic scattering in URu$_{2}$Si$_{2}$, showing contrasting behaviors along different crystal axes and suggesting a highly anisotropic and small energy scale in the basal plane affecting its superconducting properties.

Contribution

It provides a detailed analysis of anisotropic inelastic scattering and its impact on superconductivity in URu$_{2}$Si$_{2}$, highlighting the anisotropic energy scale and transport properties.

Findings

Resistivity is T-linear along the a-axis down to T_c.

Seebeck coefficient changes sign at low temperatures.

Upper critical field is larger when the magnetic field is along the less conducting direction.

Abstract

In contrast to almost all anisotropic superconductors, the upper critical field of URu$_{2}$Si$_{2}$ is larger when the field is oriented along the less conducting direction. We present a study of resistivity and Seebeck coefficient extended down to sub-Kelvin temperature range uncovering a singular case of anisotropy. When the current is injected along the c-axis URu$_{2}$Si$_{2}$ behaves as a low-density Fermi liquid. When it flows along the a-axis, even in presence of a large field, resistivity remains T-linear down to T$_{c}$ and the Seebeck coefficient undergoes a sign change at very low temperatures. We conclude that the characteristic energy scale is anisotropic and vanishingly small in the basal plane.