Observation of in-plane anomalous Hall effect in antiferromagnetic semimetal EuCd₂Sb₂

Hall effects appearing with the presence of an out-of-plane magnetic field or magnetization have

been well studied. On the other hand, in recent years, the in-plane anomalous Hall effect which is induced by an in-plane magnetic field has been

theoretically proposed based on various different types of models¹. In this work, we have

succeeded in observing large in-plane anomalous Hall effect in antiferromagnetic semimetal

EuCd₂Sb₂ films ². EuCd₂Sb₂ has only bands forming Weyl points near the Fermi level under the

magnetic field and thus is considered to be suitable for elucidating magnetotransport phenomena

originating in the Weyl points ³. We have found that in-plane anomalous Hall resistance shows

three-fold symmetry for the field rotation on the ab-plane perpendicular to the principal c-axis

with ‘in-plane’ anomalous Hall angle of 0.2 %. Moreover, the in-plane field dependence shows

clear signals, characterized by a peak structure below the saturation field and unsaturated linear

increase even above the saturation field. This is interpreted as out-of-plane Weyl points splitting

or orbital magnetization induced by the in-plane field, while the isotropic spin magnetic moments

are fully aligned along the in-plane field direction especially in the forced ferromagnetic state.

¹X. Liu et al., PRL (2013). Y. Ren et al., PRB (2016). H. Wang et al., PRL (2024). ² A. Nakamura et al., arXiv:2403.09924. ³ M. Ohno et al., Phys. Rev. B 105, L201101 (2022), A. Nakamura et al., Phys. Rev. B 109, L121108 (2024).