Frequency generation by a magnetic vortex-antivortex dipole in spin-polarized current- Prof. Stavros Komineas from the Dept. of Applied Mathematics, Univ. of Crete, Greece

A rotating vortex-antivortex dipole may be generated due to spin-polarized current flowing through a nano-aperture in a magnetic element.
The vortex dipole dynamics is analyzed using the Landau-Lifshitz equation including a Slonczewski spin-torque term for in-plane spin-current polarization.
The spin-torque acts to stabilize the vortex dipole at a definite vortex-antivortex separation. We establish that the vortex dipole is set in steady state rotational motion.
An external in-plane magnetic field can be used to tune the frequency of rotation.
We derive analytically a relation for the frequency of rotation and we find numerically steady-state rotating vortex-antivortex pairs in a more realistic model.
The rotating pair under a spin-polarized current is an attractor of the motion, therefore it is expected to be a stable state.