Magnetoresistance effects in cadmium arsenide thin films

In-plane magnetoresistance effects in the three-dimensional Dirac semimetal cadmium arsenide are studied as a function of film growth orientation, film thickness, and surface Fermi level. For films with the Fermi level near the bulk nodes, which are gapped for very thin films, a pronounced planar Hall effect is observed due to the combination of magnetoresistance effects from the Berry phase and orbital magnetoresistance. At high Fermi levels, surface state transport produces weaker magnetoresistance effects. The results are discussed in the context of detecting signatures of the chiral anomaly.