Surface states of strained thin films of the Dirac semimetal Cd3As2

Abstract

We report on the growth and transport properties of strained thin films of the three-dimensional Dirac semimetal ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$. Epitaxial heterostructures, consisting of (112)-oriented ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ films, are grown on nearly lattice matched $({\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{In}}_{x})\mathrm{Sb}$ buffer layers on (111) GaAs substrates by molecular beam epitaxy. The epitaxial coherency strain breaks the fourfold rotational symmetry, which protects the bulk Dirac nodes in ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$. All strained films exhibit the quantum Hall effect with most carriers residing in the two-dimensional states, irrespective of the sign of the biaxial stress. The Hall mobility monotonically increases as the biaxial stress is changed from compressive towards tensile. Furthermore, pronounced anisotropy is seen in the transport properties. The results show that the quantum Hall effect, which is quite similar to that of unstrained (112)-oriented films, is independent of the presence of bulk Dirac nodes. Its appearance is consistent with the topological surface states that are a characteristic of the topological ${\mathbb{Z}}_{2}$ invariant.