Rashba spin splitting-induced topological Hall effect in a Dirac semimetal-ferromagnetic semiconductor heterostructure

TL;DR

This study combines theory and experiments to demonstrate how Rashba spin-orbit coupling at a Dirac semimetal-ferromagnetic interface induces chiral spin textures, leading to a topological Hall effect that can be tuned via gate voltage.

Contribution

It reveals the emergence of a topological Hall effect driven by Rashba-induced chiral spin textures at a Dirac semimetal/ferromagnet interface, with electrostatic tunability.

Findings

Observation of an excess transverse magneto-resistance consistent with topological Hall effect.

Evidence of Rashba spin-orbit coupling inducing Dzyaloshinskii-Moriya interactions.

Gate voltage dependence demonstrates electrostatic control over spin textures.

Abstract

We use a concerted theory-experiment effort to investigate the formation of chiral real space spin texture when the archetypal Dirac semimetal Cd$_3$As$_2$ is interfaced with In$_{1-x}$Mn$_x$As, a ferromagnetic semiconductor with perpendicular magnetic anisotropy. Our calculations reveal a nonzero off-diagonal spin susceptibility in the Cd$_3$As$_2$ layer due to the Rashba spin-orbit coupling from broken inversion symmetry. This implies the presence of a Dzyaloshinskii-Moriya interaction between local moments in the In$_{1-x}$Mn$_x$As layer, mediated by Dirac electrons in the vicinal Cd$_3$As$_2$ layer, potentially creating the conditions for a real space chiral spin texture. Using electrical magnetoresistance measurements at low temperature, we observe an emergent excess contribution to the transverse magneto-resistance whose behavior is consistent with a topological Hall effect arising from the formation of an interfacial chiral spin texture. This excess Hall voltage varies with gate voltage, indicating a promising electrostatically-tunable platform for understanding the interplay between the helical momentum space states of a Dirac semimetal and chiral real space spin textures in a ferromagnet.