Separated Edge-Soliton-Mediated Dynamic Switching of Vortex Chirality and Polarity

Magnetic vortices are characterized by the senses of in-plane magnetization chirality and by the polarity of the vortex core. The electrical control of vortex polarity and chirality is highly demanded not only for fundamental understanding of spin dynamics in nanodisks under different circumstances, but also for technological applications, such as magnetic nonvolatile memories and spin torque oscillators for neuro-morphic computing. We report an alternative approach that enables one to electrically control both the vortex chirality and polarity with low energy consumption. Thorough micromagnetic simulations, we show that in thin nanodisks of diameters larger than 160 nm, with the presence of a current-induced Oersted field, the dynamic transformation of the edge solitons is able to efficiently switch both vortex chirality and polarity with low current under certain circumstances. We then develop an approach to directly write any of the four vortex states by electrical current pulses from a random state. We further investigate the switching phase diagram as a function of disk diameters. The results show that the switching process is highly size dependent. As the disk diameter becomes smaller than 160 nm, the switch of vortex core (VC) chirality and polarity always take place at the same time, resulting in an unchanged handedness before and after switching. Furthermore, the critical switch current can be as low as 3 x 10(6) A/cm(2), indicating a possible way for low current switch of vortex chirality in small disks.