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Quantum dynamics of vortices in mesoscopic magnetic disks
Model of quantum depinning of magnetic vortex cores from line defects in a
disk geometry and under the application of an in-plane magnetic field has been
developed within the framework of the Caldeira-Leggett theory. The
corresponding instanton solutions are computed for several values of the
magnetic field. Expressions for the crossover temperature Tc and for the
depinning rate \Gamma(T) are obtained. Fitting of the theory parameters to
experimental data is also presented.Comment: 8 page
Excitation modes of vortices in sub-micron magnetic disks
Classical and quantum theory of spin waves in the vortex state of a
mesoscopic sub-micron magnetic disk has been developed with account of the
finite mass density of the vortex. Oscillations of the vortex core resemble
oscillations of a charged string in a potential well in the presence of the
magnetic field. Conventional gyroscopic frequency appears as a gap in the
spectrum of spin waves of the vortex. The mass of the vortex has been computed
that agrees with experimental findings. Finite vortex mass generates a
high-frequency branch of spin waves. Effects of the external magnetic field and
dissipation have been addressed.Comment: 12 page
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