Magnetic aftereffect and Barkhausen effect in thin films of the altermagnetic candidate Mn5Si3

TL;DR

This study investigates the Hall effect in Mn5Si3 thin films, revealing magnetic relaxation and Barkhausen steps indicative of domain reorientations, providing new insights into altermagnetic behavior.

Contribution

It presents the first experimental evidence of Barkhausen steps and magnetic relaxation in altermagnetic Mn5Si3 thin films, expanding understanding of their magnetic dynamics.

Findings

Observation of time-dependent Hall voltage relaxation.

Detection of Barkhausen steps indicating domain reorientations.

Estimated Barkhausen length of around 18 nm.

Abstract

Altermagnetism as a third distinct type of collinear magnetic ordering lately attracts vivid attention. We here study the Hall effect response of micron-scale Hall bars patterned into Mn5Si3 thin films, an altermagnet candidate material. Recording transport data as a function of time, at fixed magnetic field magnitude, we observe a time-dependent relaxation of the Hall voltage qualitatively and quantitatively similar to the magnetic viscosity response well established in ferromagnetic films. In addition, the Hall voltage time traces feature clear unilateral steps, which we interpret as Barkhausen steps, i.e., as experimental evidence for abrupt reorientations of magnetic (Hall vector) domains in the altermagnetic candidate material. A quantitative analysis yields a Barkhausen length of around 18nm in the Hall bar devices with the smallest width of 100 nm.