Since the discovery of graphene, Dirac systems have attracted considerable attention due to their extraordinary properties. Recently, Dirac semimetals (DSs)-a new quantum state of matter-have been proposed. DSs can be viewed as an analogue of graphene but with linear energy dispersion in all three momentum directions. Due to the distinct electronic properties, DSs have been a fertile playground in discovering novel phenomena. In addition, it is possible to realize topological superconductivity in DSs, which plays a key role in next generation quantum computation. Shortly after theoretical predictions, several materials have been experimentally confirmed to be DSs, such as Cd₃As₂ and ZrTe₅. Here, we report magneto-transport studies on Cd₃As₂ and ZrTe₅. Shubnikov–de Haas oscillations were observed in both materials. A non-trivial Berry’s phase of π was obtained indicating the existence of Dirac fermions. However, angular dependence measurement shows different results in these two materials. Dirac fermions in ZrTe₅ show a two-dimensional nature while in Cd₃As₂ they behave like three-dimensional particles. In addition, we observed supercurrent in superconductor (Al)–DS (Cd₃As₂)–superconductor (Al) junctions. Realizing topological superconductivity is an essential step towards finding Majorana fermions which are believed to be building blocks for quantum computers.

Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.