Differences in the Resistive and Thermodynamic Properties of the Single Crystalline Chiral Superconductor Candidate SrPtAs

TL;DR

This study reports the synthesis and characterization of single crystalline SrPtAs, revealing superconducting properties consistent with prior polycrystalline results but also highlighting discrepancies in heat capacity measurements.

Contribution

First synthesis of single crystalline SrPtAs and detailed comparison of its resistive, magnetic, and thermodynamic properties with polycrystalline samples.

Findings

Superconducting transition at T_c ≈ 2.2 K from susceptibility and resistivity.

Heat capacity shows a small bulk transition at 0.7 K.

Discrepancy between thermodynamic and other measurements discussed.

Abstract

$\require{mediawiki-texvc}$The locally non-centrosymmetric superconductor SrPtAs is proposed to host a topological chiral $d$-wave state, but experimental reports have been limited to polycrystalline samples. Here we report the synthesis of single crystalline SrPtAs grown from Pb flux. SrPtAs crystallizes in the hexagonal space group $P6_{3}$/$mmc$ with lattice parameters $a$ = 4.2445(4) ${\AA}$ and $c$ = 8.9513(18) ${\AA}$. Magnetic susceptibility and electrical resistivity measurements reveal a superconducting transition at T$_c$ $\sim$2.2 K, in agreement with previous reports on polycrystalline samples. Surprisingly, heat capacity data show only a small bulk transition at 0.7 K. We discuss the possible origins of the discrepancy between the various measurements.