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We investigate the response of magnetic vortex cores in bilayer dots, a vertical stack of disk and square sublayers, to ultrashort in-plane magnetic field pulses by micromagnetic simulations. The bilayer dots adopt the advantage of switching behaviors of constituent dots; the low switching field threshold of the square is still maintained and the operating switching field range is intermediate, compared to the single-layer disk and square. Besides the usual creation and subsequent annihilation of vortex-antivortex pair reported previously, subsequent antivortex or vortex and antivortex pair during the vortex core switching process can be observed in the bilayer dot with a lateral size of about 100 nm. [ABSTRACT FROM AUTHOR]

This paper reports the micromagnetic simulations of spin-wave modes excited by spin-transfer torque for an elliptical nanomagnet sized 178\times 133\times 2.1\ nm^3. Through power spectral analysis we discovered that, for the collinear case, the excited spin-wave mode exhibits the same spatial symmetry as the initial ground state. The additional action of the Oersted field not only changes the mode pattern but also shifts the eigenfrequency from 8.24 GHz to 2.99 GHz due to the degradation of symmetry. For the non-collinear case, without taking into account the Oersted field, a tilted polarizer leads to the excitation of the quasi-uniform mode and reduces the switching time substantially. However, considering the Oersted field, the activated mode is the center mode. The simulated results indicate that the spatial symmetry of the Oersted field and the spin-torque term play crucial roles in determining the activated spin-wave eigenmodes. [ABSTRACT FROM AUTHOR]

Presents a study on the influence of the surface topology on the magnetostatic coupling between two patterned ferromagnetic layers. Two-dimensional Fourier series method; Magnetic theory; Discussion of results.

Studies the influence of interparticle interaction on the switching of recording media under a rapidly varying field. Importance of damping effect on the switching of single-domain particles (SDP); Method used to model the response of a high-speed recording system; Results of the study.