SnAs: a 4K weak type-II superconductor with non-trivial band topology

TL;DR

This study reports the synthesis and characterization of SnAs, a superconductor with non-trivial band topology, exhibiting weak type-II superconductivity at 4K, with evidence from DFT calculations, surface states, and experimental measurements.

Contribution

The paper presents the successful growth and detailed analysis of SnAs as a topologically non-trivial superconductor with comprehensive experimental and theoretical validation.

Findings

SnAs exhibits non-trivial topological surface states.

Superconductivity in SnAs is confirmed as weak type-II at 4K.

Band inversion indicates topologically non-trivial electronic structure.

Abstract

Superconductors with non-trivial band topology are emerging as one of the best avenues to study quantum anomalies and experimental realization of Majorana Fermions. This article reports the successful crystal growth of superconducting SnAs, which can have topologically non-trivial states, as evidenced in DFT (Density Functional Theory) calculations, Z2 invariants, and topologically surface state. Here, we followed a two-step method to grow SnAs crystal. The powder XRD (X-ray Diffractometry) pattern of synthesized crystal ensures that the crystal is grown in a single phase with a NaCl type cubic structure and the EDAX (Energy Dispersive X-ray Analysis) endorses the stoichiometry of the as-grown sample. The DFT calculations performed with and without the inclusion of spin-orbit coupling (SOC) show band inversion at various K symmetry points near the Fermi level. The recorded Raman spectra show two different modes, which are assigned as A1 and ETO vibrations. The ZFC (Zero-Field Cooled) & FC (Field Cooled), as well as the isothermal M-H (Magnetization vs. field) measurements, are also performed for the topological non-trivial SnAs superconductor, which eventually confirms the weak type-II superconductivity at 4K. Various other superconductivity parameters viz. kappa parameter, coherence length, and penetration depth are also calculated to probe the as-grown sample's characteristics.