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

TL;DR

This study demonstrates a gate-tunable ferromagnetic transition in a heterojunction of a Dirac semimetal and a ferromagnetic semiconductor, revealing electric field control over magnetic properties in topological materials.

Contribution

It introduces a novel heterostructure enabling efficient electric field tuning of ferromagnetism in a Dirac semimetal-semiconductor interface, highlighting a new platform for topological magnetic phenomena.

Findings

Gate voltage can tune the Curie temperature by ~10 K/MV/cm.

Tuning of $T_C$ saturates near the charge neutrality point.

Non-monotonic $T_C$ behavior suggests interaction between Dirac semimetal and ferromagnetic semiconductor.

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 $\Delta T_{\mathrm{C}}/\Delta E \sim 10$ 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.