Topological spintronics: from physics to devices

Quantum geometry, characterized by the quantum metric and Berry curvature that encode the local topology of electronic states, gives rise to intriguing physical phenomena and holds promise for novel device applications [1-3]. Here, we first report the observation of quantum metric quadrupole-induced nonlinear transport in a correlated antiferromagnet, enabling effective readout of antiferromagnetic order without external magnetic fields [4]. Subsequently, we demonstrate the generation of spin current via Berry curvature dipole in a low-symmetry Weyl semimetal, which allows efficient and robust perpendicular magnetization switching in the absence of an in-plane magnetic field [5]. Finally, we propose a cryogenic in-memory computing scheme based on magnetic topological insulators exhibiting global topology with quantized Chern numbers [6]. These advances highlight the potential of quantum geometric effects for next-generation electronic and spintronic technologies.