Harnessing magnetic switching and dynamics using electron and magnon spin currents

The manipulation, transmission, and detection of spin information require effective control of the magnetic orientation and dynamics in magnetic materials, which can be realized by the interactions between magnetic moments and spin current. In this talk, I will present our progress in using spin currents carried by conduction electrons and magnons to realize efficient magnetic switching and transmission of dynamical spin signals.

Using electron spin current, we firstly demonstrated current-induced magnetic switching via the strong spin-orbit torque from topological insulators at room temperature. We then studied the spin-orbit torque switching of a ferromagnetic Weyl semimetal, where the topological properties are manipulated by the magnetic switching. Beside electron spin current, spin angular momentum can also be transmitted by spin wave via magnon spin current. In the third work, we used magnetic domain walls to manipulate the phase and magnitude of a coherent spin wave, and in turn, investigated the domain wall motion driven by a spin wave. This mutual control can pave the way towards all-magnon computing devices. We then studied the nonreciprocal transmission of incoherent magnon currents in a coupled magnetic bilayer, which is useful for designing signal isolation devices. Finally, we extended the material system from ferromagnets to antiferromagnets. We demonstrated long-distance spin transport in antiferromagnetic insulators with easy-plane anisotropy, where the magnon eigenmodes are linearly polarized and propagate in a birefringence-like manner.

To conclude, multiple opportunities for magnetic switching and spin transport have been explored by the usage of electron and magnon spin currents, which represents an advancement towards energy-efficient and highly tunable memory and computing technologies.