Superconductivity in PtPb$_{4}$ with Possible Nontrivial Band Topology

TL;DR

This paper reports the discovery of superconductivity in PtPb4 at 2.7 K, which also exhibits signs of nontrivial topological band structure, making it a promising candidate for topological superconductivity.

Contribution

It demonstrates that PtPb4 exhibits both superconductivity and potential nontrivial topological band features, a rare combination under ambient conditions.

Findings

Superconducting transition temperature around 2.7 K.

Specific heat jump larger than weak-coupling BCS value.

Quantum oscillation data suggest topological band structure.

Abstract

Superconductivity in topological quantum materials is much sought after as it represents the key avenue to searching for topological superconductors, which host a full pairing gap in the bulk but Majorana bound states at the surface. To date, however, the simultaneous realization of nontrivial band topology and superconductivity in the same material under ambient conditions remains rare. In this paper, we study both superconducting and topological properties of a binary compound PtPb$_{4}$ ($T_c$ $\sim$ 2.7 K) that was recently reported to exhibit large Rashba splitting, inherent to the heavy 5$d$ Pt and 6$p$ Pb. We show that in PtPb$_{4}$, the specific heat jump at $T_c$ reaches $\Delta C/\gamma T_{c}$$\sim$1.70$\pm0.04$, larger than 1.43 expected for the weak-coupling BCS superconductors. Moreover, the measurement of quantum oscillation suggests the possibility for a topological band structure, which is further studied by density functional theory calculations. Our study may stimulate future experimental and theoretical investigations in this intriguing material.