Sub-nanosecond magnetic vortex reversal induced by localized resonant strain field in doped nanomagnets

Abstract

The strain-induced magnetic vortex dynamics in nanomagnets with ring-shaped impurities are investigated by means of micromagnetic simulations. It is found that the type and location of impurities can modulate the strain-stimulated spin wave spectrum of the magnetic vortex. Compared with pure nanomagnets without doping, the scattering impurities make the eigenfrequency of nanomagnets higher, while the pinning impurities lead to lower eigenfrequency. Moreover, the spin wave oscillation amplitude in a doped nanomagnet is strengthened by the gradient of exchange energy at the interface between the impurity ring and nanomagnet. The magnetic vortex polarity in a nanomagnet with specific doping schemes can be reversed in a sub-nanosecond scale by a localized resonant strain signal. Besides the switching efficiency improvement, the threshold stress of sub-nanosecond polarity reversal in nanomagnets with specific doping schemes is also reduced compared to the counterpart of nanomagnets without impurities. These results indicate that doping engineering of nanomagnets is a significant method to achieve straintronic devices with higher operating frequency and lower energy consumption.