Semi-Dirac and Dirac-node-arc phases in a (112) oriented Cd3As2 film

We investigate the electronic structure and spin-dependent densities of low-energy electron states in a (112) oriented Cd[Formula: see text]As[Formula: see text] film. We find that the thick Cd[Formula: see text]As[Formula: see text] film is a semi-Dirac material whose dispersion is linear (massless) in one direction and is quadratic (massive) in the orthogonal direction. Its spin-up and spin-down densities corresponding to linear dispersion, respectively, distribute at the top and bottom surface of the film, exhibiting the chirality of Dirac electrons, while the ones corresponding to quadratic dispersion overlap each other. In particular, an appropriate electric field vertical to the top surface of the film can result in anisotropic Rashba spin–orbit coupling and open a bandgap in the quadratic dispersions and its adjacent linear dispersions, driving a topological phase transition from a semi-Dirac-point phase to a Dirac-node-arc phase. Our findings predict a (112) oriented Cd[Formula: see text]As[Formula: see text] film to be a candidate semi-Dirac material and provide a method to find Dirac-node-arc states for experiments.