Abstract:

The surface state of a topological material is widely regarded as a promising platform for next-generation information technology, such as a topological quantum computer utilizing the Majorana zero mode. Materials exhibiting such topological surface states are rare. Moreover, there has not been a known compound with the topological normal state that transitions into a topological superconductor. Such compounds offer a unique opportunity to study the interplay between topological normal and superconducting states. In this talk, I present the angle-dependent magnetic field response of electrical transport properties of half-Heusler YPtBi in both normal and superconducting states. The angle dependence of both magnetoresistance and the superconducting upper critical field breaks the rotational symmetry of the cubic crystal structure, and the angle between the applied magnetic field and the current-carrying plane of a plate-like sample prevails. Furthermore, the measured upper critical field is notably higher than the bulk response for an in-plane magnetic field configuration, suggesting the presence of quasi-2D superconductivity. These results imply the transport properties cannot be explained solely by the bulk carrier response, requiring robust normal and superconducting surface states to flourish in YPtBi. Therefore, half-Heusler YPtBi stands out as a unique system with both topological normal and superconducting surface states.