Transport in Coherently Strained Thin Films of a 3D Dirac Semimetal

Cd₃As₂ is a 3D Dirac semimetal with degenerate band crossings at isolated points in k-space
(Dirac nodes). Most prior studies have focused on the electronic states of bulk single crystals.
Thin films of Cd₃As₂ allow for using heteroepitaxy approaches to control their electronic states.
Here, we present our studies of epitaxial thin films of Cd₃As₂ grown by molecular beam epitaxy
on (111) GaAs with relaxed In_xGa_1-xSb buffer layers. The composition of the In_xGa_1-xSb buffer
layers was varied to obtain layers that are lattice matched with the Cd₃As₂, as well as to obtain
tensile and compressively strained Cd₃As₂. We measured the strain in the Cd₃As₂ films using
high-resolution x-ray diffraction and showed that in-plane strains can be varied between 0.7%
to -0.9%, depending on the In-content of the buffer layers. The electrical transport properties
systematically vary with the magnitude of the film strain. We discuss the utility of strain
engineering to control the electronic states.