Superconductivity in topologically nontrivial material Au2Pb

TL;DR

This study investigates superconductivity in Au2Pb, revealing its nontrivial topological nature and how external stress influences its superconducting properties through experimental and theoretical analyses.

Contribution

It provides the first systematic experimental and theoretical evidence of nontrivial topological superconductivity in Au2Pb, highlighting the effects of external stress on its superconducting gap.

Findings

Superconducting transition temperature Tconset= 1.3 K.

Unusual quasi-linear temperature dependence of Hc2.

Enhanced superconducting gap under external stress.

Abstract

The search for nontrivial superconductivity in novel quantum materials is currently a most attractive topic in condensed matter physics and material science. The experimental studies have progressed quickly over the past couple of years. In this article, we report systematic studies of superconductivity in Au2Pb single crystals. The bulk superconductivity (onset transition temperature, Tconset= 1.3 K) of Au2Pb is characterized by both transport and diamagnetic measurements, where the upper critical field Hc2 shows unusual quasi-linear temperature dependence. The superconducting gap is revealed by point contact measurement with gold tip. However, when using tungsten (W) tip, which is much harder, the superconducting gap probed is largely enhanced as demonstrated by the increases of both Tconset and upper critical field (Hc2). This can be interpreted as a result of increase in density of states under external anisotropic stress imposed by the tip, as revealed by first-principles calculations. Furthermore, novel phase winding of the pseudospin texture along k-space loops around the Fermi energy is uncovered from the calculations, indicating that the observed superconductivity in Au2Pb may have nontrivial topology.