Nonlinear gyrotropic vortex dynamics in ferromagnetic dots

Guslienko, K. Yu.; Heredero, Rafael Hernández; Chubykalo‐Fesenko, O.

doi:10.1103/physrevb.82.014402

Cited by 51 publications

(43 citation statements)

References 51 publications

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“…The resulting magnetic response depends on the profile of the confining magnetostatic potential. The potential can be described either by parabolic terms 14,15 , or more precisely including higher order terms in the energy expansion [16][17][18] . Micromagnetic simulations predict significant contribution of higher order energy terms 16,17 leading to a nonlinear increase of the eigenfrequency as a function of the vortex core position.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and efficiency of magnetic vortex circulation reversal

et al. 2015

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Dynamic switching of the vortex circulation in magnetic nanodisks by fast rising magnetic field pulse requires annihilation of the vortex core at the disk boundary and reforming a new vortex with the opposite sense of circulation. Here we study the influence of pulse parameters on the dynamics and efficiency of the vortex core annihilation in permalloy (Ni80Fe20) nanodisks. We use magnetic transmission soft x-ray microscopy to experimentally determine a pulse rise time -pulse amplitude phase diagram for vortex circulation switching and investigate the time-resolved evolution of magnetization in different regions of the phase diagram. The experimental phase diagram is compared with an analytical model based on Thiele's equation describing high amplitude vortex core motion in a parabolic potential. We find that the analytical model is in a good agreement with experimental data for a wide range of disk geometries. From the outputs of the analytical model and in accordance with our experimental finding we determine the geometrical condition for dynamic vortex core annihilation and pulse parameters needed for the most efficient and fastest circulation switching. The comparison of our experimental results with micromagnetic simulations show that the micromagnetic simulations of 'ideal' disks with diameters larger than ∼250 nm overestimate nonlinearities in susceptibility and eigenfrequency. This overestimation leads to the core polarity switching near the disk boundary, which then in disagreement with experimental findings prevents the core annihilation and circulation switching. We modify the micromagnetic simulations by introducing the 'boundary region' of reduced magnetization to simulate the experimentally determined susceptibility and in these modified micromagnetic simulations we are able to reproduce the experimentally observed dynamic vortex core annihilation and circulation switching.

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Section: Introductionmentioning

confidence: 99%

Dynamics and efficiency of magnetic vortex circulation reversal

et al. 2015

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“…In the Fermi regime we find that the sound velocity increases on a constant value defined by formula (27).…”

Section: Discussionmentioning

confidence: 95%

“…For example quantum dots show interesting spin waves behavior [23]- [27]. Dynamics of the magnetic moments in the quantum plasma has also been studied.…”

Section: Introductionmentioning

confidence: 99%

Waves of spin current in magnetized dielectrics

Andreev

Kuz'menkov

2015

Int. J. Mod. Phys. B

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Spin-current is an important physical quantity in present day spintronics and it might be very usefull in the physics of quantum plasma of spinning particles. Thus it is important to have an equation of the spin-current evolution. This equation naturally appears as a part of a set of the quantum hydrodynamics (QHD) equations. Consequently, we present the set of the QHD equations derived from the many-particle microscopic Schrodinger equation, which consists of the continuity equation, the Euler equation, the Bloch equation and equation of the spin-current evolution. We use these equations to study dispersion of the collective excitations in the three dimensional samples of the magnetized dielectrics. We show that dynamics of the spin-current leads to formation of new type of the collective excitations in the magnetized dielectrics, which we called spin-current waves.

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“…In the present paper we calculated analytically the additional damping for small vortex core displacements 1. << s However, our calculations would be extended for larger vortex core displacements beyond the linear approximation [30]. We assume that there should be an enhancement of the additional damping and a decrease of the vortex gyration radius in the nonlinear regime.…”

Section: Discussionmentioning

confidence: 99%

“…(15), (18) and (19) originates from the emergent elec- i t ∂ m r must be not equal to zero. The damping tensor has been approximated to be a constant in most studies [26,27,29,30] on magnetic vortex dynamics assuming that the vortex core is positioned near the dot center. However, in the recent paper [31] it was shown by micromagnetic modeling that the gyrovector and damping parameters are changing with the vortex oscillations.…”

Section: Discussionmentioning

confidence: 99%

Effective magnetization damping for a dynamical spin texture in metallic ferromagnet

Sukhostavets

González

Guslienko

2015

Low Temperature Physics

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An additional magnetization damping for an inhomogeneous spin texture in metallic ferromagnets is calculated on the basis of the s-d exchange model. The effect of conduction electrons on the magnetization dynamics is accounted for the case of slowly varying spin texture within adiabatic approximation by using a coordinate transformation to the local quantization axis. The moving magnetic vortex in a circular nanodot made of permalloy is considered as an example. The dependence of the damping on the dot geometrical sizes is obtained. It is found that the additional damping can reach up to 50% of magnitude of the phenomenological Gilbert damping in the Landau-Lifshitz equation of magnetization motion and should be taken into account for any inhomogeneous spin texture dynamics in ferromagnetic metals.

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Nonlinear gyrotropic vortex dynamics in ferromagnetic dots

Cited by 51 publications

References 51 publications

Dynamics and efficiency of magnetic vortex circulation reversal

Dynamics and efficiency of magnetic vortex circulation reversal

Waves of spin current in magnetized dielectrics

Effective magnetization damping for a dynamical spin texture in metallic ferromagnet

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