Emergent p-Wave Superconductivity in a Dual Topological Insulator BiSe via Superconducting Proximity Effect

Abstract

The quest for anisotropic superconductors has been a long-standing pursuit due to their potential applications in quantum computing. In this regard, experimentally, d-wave and anisotropic s-wave superconducting order parameters are predominantly observed, while p-wave superconductors remain largely elusive. Achieving p-wave superconductivity in topological phases is highly desirable, as it is considered suitable for creating topologically protected qubits. To achieve topological superconductivity in the dual topological insulator BiSe, we place an s-wave superconductor NbSe₂ in its close proximity employing the van der Waals epitaxy technique. Low-temperature differential conductance measurements performed at the heterojunction exhibit a dual-dip feature with a V-shaped inner dip, a characteristic of p-wave superconductivity. This observation is corroborated by the multiband 2D Blonder–Tinkham–Klapwijk (BTK) fitting, where the inner and outer gaps exhibit p-wave and s-wave character, respectively. Furthermore, the BTK analysis reveals that the two superconducting gaps experience distinct effective critical fields and transition temperatures.