Planar Hall effect induced by spin-orbit coupling in a thin-film MnTe*

Recent developments in antiferromagnetic spintronics have demonstrated that a special case of anomalous Hall effect: planar Hall effect (PHE) or anisotropic Hall effect can be employed as a reliable read-out scheme. This has been known to originate from the spin-orbit coupling effect in many bulk antiferromagnetic crystals. Here we theoretically show that the PHE in MnTe thin films comes from the Fermi rings at the gamma point induced by a unique type of spin-orbital coupling. First-principle calculations and group-theory analysis demonstrate that the rotation symmetry of a fourth-order k dot p model has a period of π, which explains the behavior of the PHE signal in a rotating in-plane magnetic field. Furthermore, an analytical solution to the Boltzmann transport equation explicitly demonstrates that the Hall effect may originate from the spin-dependent scattering off spin-polarized defects in the antiferromagnetic order.