Superconductivity in topologically nontrivial material Au2Pb

Abstract

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 Au 2 Pb single crystals. The bulk superconductivity (onset transition temperature, T c onset =1.3 K) of Au 2 Pb is characterised by both transport and diamagnetic measurements, where the upper critical field H c2 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 T c onset and upper critical field ( H c2 ). 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 Au 2 Pb may have nontrivial topology.