Magneto-cubic and magneto-linear dependence observed in an in-plane anomalous Hall magnet

TL;DR

This study reveals complex multipolar and magnetic phase-dependent behaviors in the in-plane anomalous Hall effect of EuCd2Sb2 thin films, highlighting new off-diagonal coupling mechanisms and their temperature and field dependencies.

Contribution

It systematically characterizes the multipolar dependence of off-diagonal coupling in the in-plane AHE of a trigonal antiferromagnet, revealing magneto-cubic and magneto-linear behaviors across different magnetic phases.

Findings

Magneto-cubic dependence observed in both paramagnetic and antiferromagnetic phases.

Off-diagonal octupolar tensor component decays as inverse temperature cubed.

Magneto-linear dependence dominates in the ferromagnetic phase, persisting at high fields.

Abstract

The Hall effect, particularly that arising from in-plane magnetic field, has recently emerged as a sensitive probe of quantum geometric properties in solids. Especially in trigonal systems, in-plane anomalous Hall effect (AHE) can be explicitly induced by nontrivial off-diagonal coupling between the magnetic field and the Hall vector on the principal plane. Here we elucidate multipolar dependence of the off-diagonal coupling in the in-plane AHE, by systematically measuring on the (001) principal plane of trigonal antiferromagnet EuCd2Sb2 thin films for each magnetic phase. Around zero field, magneto-cubic dependence of anomalous Hall resistivity is clearly observed not only in the paramagnetic phase but also even in the antiferromagnetic phase. An off-diagonal component of the octupolar tensor also exhibits unconventional decay above the magnetic ordering temperature, roughly depending on the inverse temperature to the third power. In the forced ferromagnetic phase, on the other hand, magneto-linear dependence dominantly appears and notably persists up to very high fields. Our findings clarify key aspects of the off-diagonal coupling in the in-plane AHE, paving the way for its future investigations and potential applications beyond conventional expectations about the Hall effect.