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

**Authors:** Saurav Islam, Emma Steinebronn, Kaijie Yang, Bimal Neupane, Juan Chamorro, Supriya Ghosh, K. Andre Mkhoyan, Tyrel M. McQueen, Yuanxi Wang, Chaoxing Liu, Nitin Samarth  
**arXiv:** [2403.18485](https://arxiv.org/abs/2403.18485)  
**Date:** 2024-03-27  
**Summary page:** https://www.summarizepaper.com/en/paper/2403.18485v1/

## Key points

- Investigated the formation of chiral real space spin texture at the interface between Cd$_3$As$_2$ and In$_{1-x}$Mn$_x$As
- Identified non-zero off-diagonal spin susceptibility in Cd$_3$As$_2$ layer due to Rashba spin-orbit coupling
- Proposed existence of Dzyaloshinskii-Moriya interaction mediated by Dirac electrons for chiral spin texture formation
- Utilized HAADF-STEM imaging and STEM EDX mapping for sample characterization during thinning processes
- Conducted electrical magnetoresistance measurements on Hall bar devices to observe emergent behavior at low temperatures, revealing a topological Hall effect
- Data availability upon request from corresponding author or through Penn State's ScholarSphere repository
- Code availability for calculations and computational work with relevant packages accessible online or through direct inquiry
- Acknowledged funding sources including NSF grants, startup funds from University of North Texas, computational resources from Texas Advanced Computing Center and Oak Ridge National Laboratory, support from Institute for Quantum Matter and Characterization Facility at University of Minnesota

## Summary

In this study, a concerted theory-experiment effort was employed to investigate the formation of chiral real space spin texture at the interface between the Dirac semimetal Cd$_3$As$_2$ and the ferromagnetic semiconductor In$_{1-x}$Mn$_x$As with perpendicular magnetic anisotropy. The research revealed a non-zero off-diagonal spin susceptibility in the Cd$_3$As$_2$ layer, attributed to Rashba spin-orbit coupling resulting from broken inversion symmetry. This finding suggests the existence of a Dzyaloshinskii-Moriya interaction between local moments in the In$_{1-x}$Mn$_x$As layer, mediated by Dirac electrons in the adjacent Cd$_3$As$_2$ layer, potentially leading to the formation of a real space chiral spin texture. Experimental techniques such as high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and STEM energy dispersive X-ray (EDX) mapping were utilized to characterize the film surface and ensure sample integrity during thinning processes. Electrical magnetoresistance measurements conducted on Hall bar devices provided further insights into the emergent behavior observed at low temperatures. Specifically, an excess contribution to transverse magneto-resistance consistent with a topological Hall effect was identified, indicating the presence of an interfacial chiral spin texture. The study also emphasized that all data associated with results presented in both main manuscript and supplementary materials are available upon request to the corresponding author or through Penn State's ScholarSphere repository. Additionally, code availability for calculations and computational work was highlighted, with relevant packages accessible online or through direct inquiry. Acknowledgments were extended to various funding sources supporting different aspects of the project, including NSF grants, startup funds from institutions like University of North Texas, computational resources from Texas Advanced Computing Center and Oak Ridge National Laboratory, as well as support from organizations such as Institute for Quantum Matter and Characterization Facility at University of Minnesota. Individual researchers were acknowledged for their specific contributions within this collaborative effort.