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

•The critical switching current density and switching time decrease greatly.•The equilibrium position and the gyrotropic frequency variations cause the decreases.•Realizing a fast switching with lower current density.

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 equilibrium 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.