Ultrafast magnetization reversal of a nanodevice by the chirped current pulse via Spin-Orbit-Torque

Recently, Spin-Orbit Torque (SOT) is emerged as an efficient controlling knob to manipulate magnetic states by electric current. This capability is of utmost importance for potential applications in high-density and speedy processing of next-generation memory devices. Therefore, it is urgent to find a way to achieve the ultrafast reliable magnetization switching of high anisotropy FM/AFM nanoparticle with low energy cost. Purposely, we investigate the Spin-Orbit Torque (SOT) driven reversal of a high anisotropy perpendicular magnetic nanodevice by a cosine chirped current pulse(CCCP). Based on the Landau-Lifshitz-Gilbert equation, numerically we demonstrate that the CCCP, by utilizing the balance of the fieldlike and dampinglike SOT components, is capable of inducing the field-free fast and efficient magnetization reversal. For a range of frequency of the optimal CCCP, the minimal current density is significantly smaller compare to the current density of conventional SOT-reversal. The fast reversal is obtained because of the physical mechanism of stimulated energy absorption (emission) of the magnetization from(to) the CCCP before (after) crossing over the energy barrier. The pulse width does not require to be precised. We also check that the CCCP driven magnetization reversal is valid at temperature 300 K. Therefore, these findings will provide a way to realize the SOT based fast and low-cost memory device.