Discovery and synthesis of a p-wave magnet with a giant anomalous Hall susceptibility.

Recently, A. Hellenes et al. proposed a p-wave magnet without the need for a Pomeranchuk instability or strong electron-electron interactions (arXiv:2309.01607). We demonstrate the experimental realization of an antiferromagnetic material satisfying the symmetry requirements for p-wave spin polarization in momentum space, based on X-ray and neutron scattering experiments. A series of large single crystals is synthesized by the high vacuum floating zone technique and their structural, electronic and magnetic properties are thoroughly characterized. In consequence of relativistic spin-orbit coupling, the p-wave state acquires a tiny net magnetization and there emerges a large anomalous Hall effect with Hall angle as large as 3~4%; much larger than the anomalous Hall effect in known d-wave and g-wave altermagnet candidates. Neutron and x-ray scattering help to identify various magnetic orders in the phase diagram, some of which have much smaller anomalous Hall effect. The results are discussed based on electronic structure models and essential symmetry arguments.