Quantum Hall effect due to surface states in (001)-plane cadmium arsenide thin films

We report transport studies of gated Hall bar structures fabricated from (001)-oriented epitaxial thin films of cadmium arsenide, a three-dimensional Dirac semimetal, in magnetic fields up to 45 T. This orientation does not host Fermi arc-type surface states because the Dirac nodes project onto the same point in the surface Brillouin zone. Recent developments in the growth of these layers have resulted in films with quantum mobilities exceeding 4,000 cm²/Vs. We explain the quantum Hall effect, which prominently features plateaus at even and odd filling factors across a range of carrier density, in terms of a surface state different from the Fermi arc-type states thought to exist on other surfaces, underlining differences between these measurements and those in the more widely studied (112)-plane films.