Unusual quantum Hall effect in ultrathin films of the Dirac semimetal Cd₃As₂

The synthesis of thin films of the Dirac semimetal (DSM) Cd₃As₂ by molecular beam epitaxy (MBE) provides an attractive avenue for studying novel phenomena in a DSM as a function of quantum confinement and chemical potential. Here, we use MBE to grow 10 nm Cd₃As₂ thin films on miscut GaAs (111)B substrates with a GaSb buffer layer. We measure electronic transport in lithographically-patterned top-gated Hall bar devices as a function of gate voltage and magnetic field at T = 20 mK. Apparent Quantum Hall plateaus with the filling factor v = 1, 2, 4, 6, 8, 10… are observed by varying the gate voltage at µ₀H = 9 T. At chemical potentials close to the Dirac point, the magnetic field dependence of the longitudinal and transverse resistivity show transitions directly into the v = 1 or v = 2 quantum Hall states without any sign of quantum oscillations or plateaus at higher filling factors. We will interpret these quantum Hall data using in vacuo angle-resolved photoemission spectroscopy investigation and theoretical calculations of the band structure of ultrathin Cd₃As₂ films.