Off-centred immobile magnetic vortex under influence of spin-transfer torque

Formation of the 'dip' structure which foregoes switching of magnetic vortex polarity is studied numerically in magnetic nanodisc. A new method based on influence of the spin-transfer torque is used. The method allows one to obtain the dip structure for immobile vortex which significantly improves studying accuracy in comparison with the case of moving vortex. Free out-of-plane vortices as well as in-plane vortices pinned on hole defects are considered. It is shown that the process of the dip formation is different for free and pinned vortices and direction of the dip does not directly depend on the vortex polarity.