Hybrid Devices

Dirac semimetals exhibits unique electronic structures, featuring three-dimensional bulk Dirac nodes and unconventional surface states. The possibility of opening a gap in the density of states in the bulk opens up to possibility to directly probe topological protected surface state using transport measurements. Furthermore, interfaces with conventional superconductors allow for studying proximity effects, and, potentially, topological superconductivity. Epitaxial Aluminum has been demonstrated to induce hard gap in coplanar junctions in InAs nanowires and quantum wells¹, thanks to the high transparency of the interface, which minimizes the quasiparticle poisoning. Here, we present transport measurement on Cd₃As₂ thin films. Quantum oscillations and Hall effect measurements conclusively show that in sufficiently thin films, the transport is carried by the surface states, with a negligible contribution of the bulk. We demonstrate the growth of epitaxial aluminum to induce a superconducting gap in the material by proximity effect. We present measurements of the current-voltage characteristics of these hybrid junctions.

¹ Kjaergaard, M. et al. Nat. Comm. 7, 12841 (2016).