Dynamics of a magnetic vortex-antivortex dipole in spin-polarized current

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• Prof Stavros Komineas, University of Crete
• Thursday 14 June 2012, 13:45-15:00
• Theory Library.

If you have a question about this talk, please contact Dr Dimitri M Gangardt.

Mesoscopic magnetic elements with sizes in the sub-micrometer scale are routinely fabricated in many laboratories and measurements can be made at very small length and time scales. The microstructure of ferromagnetic materials is described by the local magnetization vector and its dynamics obeys the Landau-Lifshitz equation. We study the dynamics of a vortex-antivortex (VA) dipole which may be generated due to spin-polarized current flowing through a magnetic element. We establish that the vortex dipole is set in steady state rotational motion, thus the system acts as a spin-transfer nano-oscillator (STNO). The frequency of rotation is due to two independent forces: the interaction between the two vortices and an external in-plane magnetic field. The nonzero skyrmion number of the dipole is responsible for both forces giving rise to rotational dynamics. The spin-torque acts to stabilize the rotational motion. We give analytical and numerical results for the frequency of rotation and VA dipole features as functions of the parameters.

This talk is part of the Theoretical Physics Seminars series.

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