Efficiently gate-tunable ferromagnetism in ferromagnetic semiconductor-Dirac semimetal p-n heterojunctions

Abstract

We use molecular beam epitaxy to develop a gate tunable p-n heterojunction that interfaces a canonical Dirac semimetal, Cd${}_3$As${}_2$, and a ferromagnetic semiconductor, In${}_{1-x}$Mn${}_x$As, with perpendicular magnetic anisotropy. Measurements of the anomalous Hall effect in top-gated Cd${}_3$As${}_2$/In${}_{1-x}$Mn${}_x$As devices show that the ferromagnetic Curie temperature ($T_{\mathrm{C}}$) can be efficiently tuned using a modest gate voltage of $\sim 10$ V, corresponding to a sensitivity to electric field ($E$) of $\hat{I}”T_{\mathrm{C}}/\hat{I}”E\sim 10$ K/MV/cm). The voltage tuning of $T_{\mathrm{C}}$ saturates near the charge neutrality point of Cd${}_3$As${}_2$ and vanishes at positive gate voltage in appropriately designed heterostructures. This non-monotonic behavior cannot be explained solely by hole-mediated ferromagnetism in the In${}_{1-x}$Mn${}_x$As alone, suggesting an interaction between the Dirac semimetal and the ferromagnetic semiconductor. Our results identify Cd${}_3$As${}_2$/In${}_{1-x}$Mn${}_x$As heterojunctions as a potentially attractive platform for studying emergent phenomena arising from the interplay between broken symmetry, topology, and magnetism in a topological semimetal.