Reduced switching current density with an off-centered nanocontact in a confined structure

We investigate the dependence of switching current density and switching time on the nanocontact size and position driven by an out-of-plane spin-polarized current in a confined nanocontact structure using micromagnetic simulations, It is found that the critical switching current density and switching time decrease greatly when the nanocontact shifts from the disk center. The analytical calculations On the basis of Thiele equation demonstrate that the equilibriurn position shift and the instantaneous gyrotropic frequency variation result in these decreases. Our findings present an additional efficient means for ultrafast switching of magnetic vortices. (C) 2015 Elsevier B.V. All rights reserved.