Superconducting proximity effect in topological Dirac materials

Inducing superconductivity in topological materials stimulates the formation of novel quantum states of matter, including the Majorana zero mode. Besides the original prediction in 3D topological insulators, the notion of topological phases has been generalized to different dimensions and extended to the higher-order states.

In the last few years, our research has demonstrated the possibility of realizing the topological superconductivity in engineered 3D topological insulators [1], 3D Dirac semimetals [2,3], and their 1D hinge states. Particularly, Cd₃As₂ is predicted to be a higher-order topological semimetal, possessing three-dimensional bulk Dirac fermions, two-dimensional Fermi arcs [4], and one-dimensional hinge states [5] or non-Hermitian states [6]. These topological states have different characteristic length scales in electronic transport. We show that the superconducting proximity effect can also be a sensitive probe for distinguishing these states.