Quantum Transport Evidence for the Three-Dimensional Dirac Semimetal Phase in Cd3As2

We report the quantum transport properties of Cd3As2 single crystals in a magnetic field. A large linear quantum magnetoresistance is observed near room temperature. With decreasing temperature, the Shubnikov-de Haas oscillations appear in both the longitudinal resistance Rxx and the transverse Hall resistance Rxy. From the strong oscillatory component Delta Rxx, a linear dependence of the Landau index n on 1/B is obtained, and it gives an n-axis intercept between 1/2 and 5/8. This clearly reveals a nontrivial [pi] Berry's phase, which is a distinguished feature of Dirac fermions. Our quantum transport results provide bulk evidence for the existence of a three-dimensional Dirac semimetal phase in Cd3As2.