Weakly Coupled Type-II Superconductivity in a Laves compound ZrRe2

TL;DR

This study investigates the superconducting properties of ZrRe2, a hexagonal Laves compound, revealing it as a weakly coupled type-II superconductor with a transition temperature above 6.1 K and a large upper critical field.

Contribution

The paper provides comprehensive experimental and theoretical analysis of ZrRe2, highlighting its weak coupling and detailed superconducting parameters, which were not previously characterized.

Findings

Superconducting transition above 6.1 K

Large upper critical field approaching Pauli limit

Weak electron-phonon coupling indicated by heat capacity

Abstract

We present a comprehensive investigation of the superconducting properties of ZrRe2, a Re-based hexagonal Laves compounds. ZrRe2 crystallizes in a C14-type structure (space group P63/mmc), with cell parameters a=b=5.2682(5) and c=8.63045 . Resistivity and magnetic susceptibility data both suggest that ZrRe2 exhibits a sharp superconducting transition above 6.1 K. The measured lower and upper critical fields are 6.27 mT and 12.77 T, respectively, with a large upper critical field that approached the Pauli limit.Measurements of the heat capacity confirm the presence of bulk superconductivity, with a normalized specific heat change of 1.24 and an electron-phonon strength of 0.69 . DFT calculations revealed that the band structure of ZrRe2 is intricate and without van-Hove singularity. The observed large specific heat jump, combined with the electron-phonon strength , suggests that ZrRe2 is a weakly coupled type II superconductor.