Nonuniform Current-Driven Formation and Displacement of the Magnetic Compensation Point in Variable-Width Nanoscale Ferrimagnets.

Nano- and microstructures based on ferrimagnets can demonstrate high efficiency and dynamics of current-induced magnetization switching combined with high stability of spin textures such as bubble domains and skyrmions, which are of practical importance for the development of spintronics and spin-orbitronics. This set of features is usually associated with magnetic momentum or angular momentum compensation states. Here, we experimentally show that the compensation state can be realized locally using nonuniform Joule heating. This effect is observed in the variable-width current guide made of the ferrimagnetic W/CoTb/Ru thin films, where the position of a region heated to the compensation temperature depends linearly on the current pulse amplitude. This approach makes it possible to observe the simultaneous coexistence of Co-dominant and Tb-dominant regions, where current pulses induce spin-orbit torques in opposite directions, leading to local magnetization switching. It is found that the position of a Néel domain wall constraining the switched region lies in the vicinity of the coordinate corresponding to the compensation point but does not coincide with it due to high mobility under the action of spin current. Our findings open an alternative approach for engineering of ferrimagnetic nanodevices with advanced properties for future applications in spintronics, spin-orbitronics, and nanoelectronics.