Planar Hall effect caused by the memory of antiferromagnetic domain walls in Mn$_3$Ge

TL;DR

This study investigates the planar Hall effect in Mn₃Ge, revealing a temperature- and field-dependent memory effect in antiferromagnetic domain walls that could be utilized for data storage.

Contribution

It demonstrates the manipulation and erasure of the PHE memory effect in Mn₃Ge through magnetic and thermal cycling, extending understanding of antiferromagnetic domain wall behavior.

Findings

Memory effect can be erased by magnetic fields >0.8 T or temperatures above T_N.

PHE amplitude differs with zero-field and field thermal cycling.

PHE to AHE ratio decreases with increasing temperature.

Abstract

In Mn$_3$X (X=Sn, Ge) antiferromagnets domain walls are thick and remarkably complex because of the non-collinear arrangement of spins in each domain. A planar Hall effect (PHE), an electric field perpendicular to the applied current but parallel to the applied magnetic field, was recently observed inside the hysteresis loop of Mn$_3$Sn. The sign of the PHE displayed a memory tuned by the prior orientation of the magnetic field and its history. We present a study of PHE in Mn$_3$Ge extended from room temperature down to 2 K and show that this memory effect can be manipulated by either magnetic field or thermal cycling. We show that the memory can be wiped out if the prior magnetic field exceeds 0.8 T or when the temperature exceeds $T_\mathrm{N}$. We also find a detectable difference between the amplitude of PHE with zero-field and field thermal cycling. The ratio between the PHE and the anomalous Hall effect (AHE) decreases slightly as temperature is increased from 2 K to $T_{\rm{N}}$, tracks the temperature dependence of magnetization. This erasable memory effect may be used for data storage.