Gate-tunable ferromagnetism in epitaxially grown Dirac semimetal-ferromagnetic semiconductor heterostructures

The coexistence of time-reversal and inversion symmetry in Dirac semimetals (DSMs) is responsible for topologically protected, spin-degenerate bulk states with Dirac dispersion. Breaking either of these symmetries results in a Weyl semimetal with broken Kramers degeneracy. This motivates the development of materials platforms wherein an external parameter (such as a gate voltage) is used to break a relevant symmetry (such as time-reversal) in a DSM. We explore this concept by using molecular beam epitaxy to interface a canonical DSM, Cd3As2, with a ferromagnetic semiconductor, (In,Mn)As, with perpendicular magnetic anisotropy. Measurements of the anomalous Hall effect (AHE) in top-gated Cd3As2/(In,Mn)As devices show that the ferromagnetic Curie temperature is highly gate-tunable. We map out the AHE in these heterostructures as a function of sample structure and chemical potential. Model Hamiltonian calculations, supported by density functional theory, provide insight into the observed behavior.