Superconductivity in topologically nontrivial material Au2Pb

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 characterised 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. Researchers in China have uncovered evidence for a new type of superconductivity in an old alloy. Jian Wang from Peking University and co-workers measured the superconducting properties of gold-lead (Au2Pb) and observed what could be an unusual effect known as topological superconductivity–superconductivity that arises due to a particular electronic structure. The researchers measured the low temperature resistivity of a single crystal of Au2Pb and confirmed that it is a superconductor. Simulations indicated that its superconductivity arises from its electronic structure, which has a nontrivial topological arrangement. Superconducting materials enable ultrasensitive sensors of magnetic fields and powerful magnets, but they usually exhibit their unusual properties only at low temperatures. Materials that exhibit superconductivity in new and unusual ways are of interest because they may open the door for ways to circumvent these limitations.