Constraints on proximity-induced ferromagnetism in a Dirac semimetal (Cd3As2)/ferromagnetic semiconductor (Ga1-xMnxSb) heterostructure

Breaking time-reversal symmetry in a Dirac semimetal Cd3As2 through doping with magnetic ions or by the magnetic proximity effect is expected to cause a transition to other topological phases (such as a Weyl semimetal). To this end, we investigate the possibility of proximity-induced ferromagnetic ordering in epitaxial Dirac semimetal (Cd3As2)/ferromagnetic semiconductor (Ga1-xMnxSb) heterostructures grown by molecular beam epitaxy. We report the comprehensive characterization of these heterostructures using structural probes (atomic force microscopy, x-ray diffraction, scanning transmission electron microscopy), angle-resolved photoemission spectroscopy, electrical magnetotransport, magnetometry, and polarized neutron reflectometry. Measurements of the magnetoresistance and Hall effect in the temperature range 2-20 K show signatures that could be consistent with either a proximity effect or spin-dependent scattering of charge carriers in the Cd3As2 channel. Polarized neutron reflectometry sets constraints on the interpretation of the magnetotransport studies by showing that (at least for temperatures above 6 K) any induced magnetization in the Cd3As2 itself must be relatively small (<14emu/cm3).