Even-in-magnetic field part of transverse resistivity as a probe of magnetic transitions

TL;DR

This paper demonstrates that the even component of transverse resistivity, often overlooked, can effectively probe magnetic transitions, as shown in ferromagnets and altermagnetic materials like Mn5Si3.

Contribution

It reveals that the even part of transverse resistivity contains valuable information about magnetic states, challenging the common view that it is solely an artefact.

Findings

The even transverse resistivity in CoFeB includes anisotropic magnetoresistance effects.

In Mn5Si3, the even resistivity component signals a magnetic transition below 80 K.

Carefully controlled experiments can extract meaningful magnetic information from the even resistivity component.

Abstract

The component of the resistivity tensor $\rho_{ij}$ corresponding to voltage transverse to both an applied current and a magnetic field can be separated into odd and even parts with respect to the applied magnetic field. The former contains information, for example, about the ordinary or anomalous Hall effect. The latter is often ascribed to experimental artefacts and ignored. Here, we show that upon suppressing these artefacts in carefully controlled experiments, useful information remains. We first investigate the well-explored ferromagnet CoFeB, where the even part of $\rho_{yx}$ contains a contribution from the anisotropic magnetoresistance, which we confirm by Stoner--Wohlfarth modelling. We then apply our approach to magnetotransport measurements of $\rm Mn_5Si_3$ thin films, which undergo a transition from non-collinear to an altermagnetic collinear state. In this material, the even part of the transverse signal is sizable only in the low-spin-symmetry phase below $\approx 80$~K. Transverse resistivity measurements thus offer a simple and readily available probe of magnetic order transitions.