Field-angle-dependent specific heat measurements and gap determination of a heavy fermion superconductor URu2Si2

TL;DR

This study investigates the superconducting gap structure of URu2Si2 through field-angle-dependent specific heat measurements and microscopic theoretical analysis, revealing point nodes and Pauli effects that influence its superconducting properties.

Contribution

It provides the first detailed experimental and theoretical analysis of the gap structure in URu2Si2, highlighting the role of point nodes and Pauli effects in its superconductivity.

Findings

Distinct field dependence of Sommerfeld coefficient 3(H) in different orientations

Evidence of point nodes and Pauli paramagnetic effects in URu2Si2

Possible first order transition of Hc2 at low temperatures

Abstract

To identify the superconducting gap structure in URu2Si2 we perform field-angle-dependent specific heat measurements for the two principal orientations in addition to field rotations, and theoretical analysis based on microscopic calculations. The Sommerfeld coefficient \gamma(H)'s in the mixed state exhibit distinctively different field-dependence. This comes from point nodes and substantial Pauli paramagnetic effect of URu2Si2. These two features combined give rise to a consistent picture of superconducting properties, including a possible first order transition of Hc2 at low temperatures.