Coexisting Topological Hinges and 1D Rashba States in Bi0.97Sb0.03 Revealed by the Josephson Effect.

Bhattacharyya, Biplab; de Wit, Stijn R; Wu, Zhen; Huang, Yingkai; Golden, Mark S; Brinkman, Alexander; Li, Chuan · ACS Nano · 2026

basic_science · Level V

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Abstract

Second-order topological insulating (SOTI) states in three-dimensional materials are helical one-dimensional hinge states. Inducing superconductivity in these states leads to gapless bound states, characterized by the 4π-periodic current-phase relation. Here, we provide evidence of the topologically protected hinge states in Dirac semimetal Bi0.97Sb0.03 nanoflakes by an unconventional interference pattern in a magnetic field and the 4π-periodic supercurrent carried by these states via the suppressed first and third Shapiro steps. Tight-binding simulations confirm the presence of multiple hinge modes, supporting our interpretation of Bi0.97Sb0.03 as a prototypical designable SOTI platform. The quantum confinement effect is identified by a quasi-one-dimensional bulk transport, and the confined Rashba states are responsible for the broadened hinge states.