Topological magnets for innovating quantum electronics

Abstract Macroscopic responses of magnets are often governed by magnetization and thus have been restricted to ferromagnets. However, such responses are found strikingly large in the newly developed topological magnets, breaking the conventional scaling with magnetization. Taking the antiferromagnetic Weyl semimetals as a prime example, we highlight the two central ingredients driving the significant macroscopic responses: the Berry curvature enhanced due to nontrivial band topology in momentum space, and the cluster magnetic multipoles in real space and we show our recent results on the electrical switching of the chiral antiferromagnetic state in its heterostructure using heavy metals and the tunneling magnetoresistance effect using all antiferromagnetic tunnel junctions. Besides, recent studies have indicated that topological magnets exhibit a gigantic anomalous Nernst effect that is a few orders of magnitude larger than previously thought according to its linear relationship to magnetization. Topological electronic structures such as nodal points, lines, and planes are found to generate large Berry curvature and enhance the transverse responses in magnetic states. The discoveries of the novel thermoelectric properties of thin films of recently developed topological magnets pave the path for their application of these effects for the fabrication of heat current sensors.