Extrinsic to intrinsic mechanism crossover of anomalous Hall effect in the Ir-doped MnPtSn Heusler system

TL;DR

This study investigates how substituting Ir for Pt in MnPtSn alters the mechanisms of the anomalous Hall effect, shifting from extrinsic to intrinsic dominance, supported by experimental and theoretical evidence.

Contribution

It demonstrates a crossover from extrinsic to intrinsic AHE mechanisms via Ir doping, highlighting control over band topology in Heusler systems.

Findings

Net magnetic moment decreases with Ir doping.

Anomalous Hall resistivity increases with Ir doping.

Intrinsic AHE becomes dominant in Ir-doped samples.

Abstract

Recent findings of large anomalous Hall signal in nonferromagnetic and nonferrimagnetic materials suggest that the magnetization of the system is not a critical component for the realization of the anomalous Hall effect (AHE). Here, we present a combined theoretical and experimental study demonstrating the evolution of different mechanisms of AHE in a cubic Heusler system MnPt$_{1-x}$Ir$_x$Sn. With the help of magnetization and neutron diffraction studies, we show that the substitution of nonmagnetic Ir in place of Pt significantly reduces the net magnetic moment from 4.17 $ \mu _B$/f.u. in MnPtSn to 2.78 $ \mu _B$/f.u. for MnPt$_{0.5}$Ir$_{0.5}$Sn. In contrast, the anomalous Hall resistivity is enhanced by nearly three times from 1.6 $ \mu \Omega $ cm in MnPtSn to about 5 $ \mu \Omega $ cm for MnPt$_{0.5}$Ir$_{0.5}$Sn. The power law analysis of the Hall resistivity data suggests that the extrinsic contribution of AHE that dominates in the case of the parent MnPtSn almost vanishes for MnPt$_{0.5}$Ir$_{0.5}$Sn, where the intrinsic mechanism plays the major role. The experimental results are well supported by our theoretical study, which shows a considerable enhancement of the spin-orbit coupling when Ir is introduced into the system. Our finding of a crossover of the anomalous Hall effect with chemical engineering is a major contribution toward the recent interest in controlling the band topology of topological materials, both in bulk and thin-film forms.