Quasi-static magnetization dynamics in a compensated ferrimagnetic half-metal -- Mn$_2$Ru$_x$Ga

TL;DR

This paper introduces a novel method combining anomalous Hall effect measurements, torque models, and hysteresis modeling to accurately analyze magnetic anisotropy and quasi-static magnetization dynamics in compensated ferrimagnetic half-metals, specifically Mn$_2$Ru$_x$Ga.

Contribution

It develops an innovative approach to determine anisotropy constants and validate macrospin models for complex magnetization behavior in MRG thin films.

Findings

Accurate determination of anisotropy constants using Hall voltage curve fitting.

Validation of macrospin model with FORC and Preisach hysteresis models.

Effective modeling of complex magnetization dynamics with hysteronic and torque models.

Abstract

Exploring anisotropy and diverse magnetization dynamics in specimens with vanishing magnetic moments presents a significant challenge using traditional magnetometry, as the low resolution of existing techniques hinders the ability to obtain accurate results. In this study, we delve deeper into the examination of magnetic anisotropy and quasi-static magnetization dynamics in \mrg\,(MRG) thin films, as an example of a compensated ferrimagnetic half-metal, by employing anomalous Hall effect measurements within a tetragonal crystal lattice system. Our research proposes an innovative approach to accurately determine the complete set of anisotropy constants of these MRG thin films. To achieve this, we perform anomalous Hall voltage curve fitting, using torque models under the macrospin approximation, which allow us to obtain out-of-plane anisotropy constants $K_1=4.0\times10^4$ J m$^{-3}$ ($K_1/M=0.655$\,T) and $K_2=2.54\times10^4$ J m$^{-3}$ ($K_2/M=0.416$\,T), along with a weaker in-plane anisotropy constant $K_3=3.48\times10^3$ J m$^{-3}$ ($K_3/M=0.057$\,T). By additionally employing first-order reversal curves (FORC) and classical Preisach hysteresis (hysterons) models, we are able to validate the efficacy of the macrospin model in capturing the magnetic behavior of MRG thin films. Furthermore, our investigation substantiates that the complex quasi-static magnetization dynamics of MRG thin films can be effectively modelled using a combination of hysteronic and torque models. This approach facilitates the exploration of both linear and non-linear quasi-static magnetization dynamics, in the presence of external magnetic field and/or current-induced effective fields, generated by the spin-orbit torque and spin transfer torque mechanisms.