Structure and physical properties of the noncentrosymmetric superconductor Mo3Al2C

TL;DR

This study synthesizes and characterizes the noncentrosymmetric superconductor Mo3Al2C, revealing its critical temperature, electronic structure, and superconducting properties, and suggests further research on gap anisotropy and triplet pairing components.

Contribution

It provides comprehensive experimental and theoretical analysis of Mo3Al2C's structure, electronic properties, and superconducting parameters, highlighting its strong coupling nature and the need for single-crystal studies.

Findings

Superconducting transition at Tc ~ 9.2 K

Density of states dominated by Mo d-orbitals

Moderately-to-strongly coupled superconductor

Abstract

We have synthesized polycrystalline samples of the noncentrosymmetric superconductor Mo3Al2C by arc and RF melting, measured its transport, magnetic and thermodynamic properties, and computed its band structure. Experimental results indicate a bulk superconducting transition at Tc ~ 9.2 K, while the density of states at the Fermi surface is found to be dominated by Mo d-orbitals. Using the measured values for the lower critical field Hc1, upper critical field Hc2, and the specific heat C, we estimated the thermodynamic critical field Hc(0), coherence length {\xi}(0), penetration depth {\lambda}(0), and the Ginzburg-Landau parameter {\kappa}(0). The specific heat jump at Tc, {\Delta}C/{\gamma}Tc = 2.14, suggests that Mo3Al2C is moderately-to-strongly coupled, consistent with the fast opening of the gap, as evidenced by the rapid release of entropy below Tc from our electronic specific heat measurements. Above 2K the electronic specific heat exhibits the power law behavior, suggesting that synthesis of single crystals and measurements at lower temperature are needed to establish whether the gap is anisotropic. The estimated value of the upper critical field Hc2(0) is close to the calculated Pauli limit, therefore further studies are needed to determine whether the absence of an inversion center results in a significant admixture of the triplet component of the order parameter.