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

No abstract

The search for unconventional superconductivity in Weyl semimetal materials is currently an exciting pursuit, since such superconducting phases could potentially be topologically nontrivial and host exotic Majorana modes. The layered material TaIrTe 4 is a newly predicted time-reversal invariant type II Weyl semimetal with minimum Weyl points. Here, by a systematical study based on electrical transport measurements at ultralow temperature and in ultrahigh magnetic field, we discover that TaIrTe 4 crystals exhibit quasi-one-dimensional (quasi-1D) superconductivity with an onset transition temperature (T c ) up to 1.54 K, and show strong Shubnikov de Haas quantum oscillations. The normalized upper critical field h * (T/T c ) behavior indicates that the discovered superconductivity is unconventional with the p-wave pairing. The superconductivity is observed to be uniform on the sample surface with a V-shaped superconducting gap by scanning tunneling spectroscopy (STS). The STS further visualizes Fermi arc surface states that are consistent with the previous angle-resolved photoemission spectroscopy results. Both the transport and STS measurements reveal that the superconductivity 2 occurs in the surface states and exhibits the quasi-1D features. Our results suggest that TaIrTe 4 is a promising platform to explore topological superconductivity.3