Normal modes of spin excitations in magnetic nanoparticles

Grimsditch, M.; Leaf, Gary K.; Kaper, Hans G.; Karpeev, Dmitry; Camley, R. E.

doi:10.1103/physrevb.69.174428

Cited by 74 publications

(53 citation statements)

References 25 publications

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“…Since the Zeeman field contribution to the total torque is negligible compared to the others, the large torques exerting on the vortex cores result primarily from changes in the positions of vortex cores and in the magnitudes of their M z / M s values. Such spin wave modes with large amplitudes can be distinguished from spin wave modes typically excited from several other ways in micrometerscale elements, such as by tilting and rotating M orientations, 1,8,17 as well as by applying an H a . With these findings mentioned above, we also investigated an injection of spin waves strongly radiated from a well-known vortex state in a disk shaped magnetic element into a long-stripe magnetic-film waveguide.…”

Section: Radiation Of Spin Waves From Magnetic Vortex Cores By Their mentioning

confidence: 99%

“…[2][3][4] Both theoretical and experimental studies have thus been increased in numbers for the exploration of the spatial and temporal characteristics of spin waves excited in micrometer-scale magnetic elements. [5][6][7][8][9][10][11][12][13][14][15][16][17] It is known that the characteristic properties of spin waves are determined by the intrinsic material parameters of exchange and dipole interactions and an external magnetic field as well as the size and shape of a system. [5][6][7][8][9] Fundamentally, it has been of great interest how the frequencies and spatial configurations of their eigenmodes are governed by these parameters.…”

Section: Radiation Of Spin Waves From Magnetic Vortex Cores By Their mentioning

confidence: 99%

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Radiation of spin waves from magnetic vortex cores by their dynamic motion and annihilation processes

Lee

Choi

Kim

2005

Applied Physics Letters

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Section: Radiation Of Spin Waves From Magnetic Vortex Cores By Their mentioning

confidence: 99%

Section: Radiation Of Spin Waves From Magnetic Vortex Cores By Their mentioning

confidence: 99%

Radiation of spin waves from magnetic vortex cores by their dynamic motion and annihilation processes

Lee

Choi

Kim

2005

Applied Physics Letters

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“…Several studies on magnetic excitations in various thinfilm elements have been reported, including wires, [3][4][5][6][7] rectangles, 4,[8][9][10] circular disks 2,[11][12][13][14][15][16][17][18][19] and squares [20][21][22][23][24] with closure domains, rings, 25 and several other elementary shapes. In all examples listed above, the samples studied were essentially two-dimensional ͑2D͒, i.e., thickness effects are not important as far as the profile of the dynamic mode is concerned.…”

Section: Introductionmentioning

confidence: 99%

Calculations of three-dimensional magnetic normal modes in mesoscopic permalloy prisms with vortex structure

2007

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Static flux-closure structures in three-dimensional ͑3D͒ mesoscopic ferromagnets are known to differ quite significantly from their 2D counterparts. How these differences reflect in the dynamic properties of the magnetization is, to date, an open question. Micromagnetic simulations are employed to study the normal modes of magnetic oscillations in thick ͑60-80 nm͒ rectangular Permalloy prisms with 3D Landau-type flux-closure domain structure. Various magnetic normal modes are excited by a short field pulse and extracted using methods based on Fourier analysis. In particular, well-defined modes in the range of a few GHz are identified as oscillations of vortices, domain walls, and as excitations localized in the corners. The asymmetric Bloch wall in the center of the 3D Landau structure wall is a genuinely three-dimensional feature and thus gives rise to effects which were not reported in previous studies on 2D systems. It is argued that experimental evidence of these findings can be obtained.

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“…Micromagnetic simulation is one of the most optimal tools, and is particularly efficacious in the study of the spin dynamics of dipole-exchange SWs in patterned elements [13], compared with current experimental techniques that are deficient in detecting SWs of wavelengths smaller than 50 nm, and compared with analytic approaches that are unsuitable for considering exchange and dipolar interactions simultaneously in restricted geometries [4,14]. In the micromagnetic approach, the dynamics of the magnetization (M) distribution within a magnet is described by the Landau-Lifshitz-Gilbert (LLG) equation of motion [15], @M=@t ÿ M H eff =M s M @M=@t , M s jMj with the phenomenological damping constant and the gyromagnetic ratio .…”

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confidence: 99%

Strong Radiation of Spin Waves by Core Reversal of a Magnetic Vortex and Their Wave Behaviors in Magnetic Nanowire Waveguides

et al. 2007

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We conducted micromagnetic numerical studies on the strong radiation of spin waves (SWs) produced by the magnetic-field-induced reversal of a magnetic vortex core, as well as their wave behaviors in magnetic nanowires. It was found that the radial SWs can be emitted intensively from a vortex core in a circular dot by virtue of localized large torques employed at the core, and then can be injected into a long nanowire via their contact. These SWs exhibit wave characteristics such as propagation, reflection, transmission, interference, and dispersion. These results offer a preview of the generation, delivery, and manipulation of SWs in magnetic elements, which are applicable to information-signal processing in potential SW devices. DOI: 10.1103/PhysRevLett.98.087205 PACS numbers: 75.30.Ds, 75.40.Gb, 75.40.Mg Spin-wave (SW) excitations in bulk or thin-film ferromagnets have long been fundamentally interesting topics in the research area of magnetism [1,2]. In particular, SWs in nanodots, nanowires, and etc., are of revived interest, both theoretically and experimentally, due to progress in submicron (or less) sized sample preparations [3], as well as to the different underlying physics of nanosize elements from that of bulk magnets. Considerable progress in the understanding of spin excitation spectra in confined geometries has been achieved by theoretical approaches, micromagnetic simulations, and sub-ns time-resolving and sub-m space-resolving measurement techniques. For example, for magnetically saturated elements, not only fundamentals such as the dispersion relation of SWs are derived [4,5], but their propagation, reflection, and tunneling are also verified by various measurement techniques [5][6][7]. Furthermore, using a magnetic vortex (MV) state in submicron-size elements, the SW modes over the vortex ground state as well as translational vortex motion in the low-frequency regime have been explored by theoretical predictions [8] and experimental verifications [9].Quite recently, SWs propagating at speeds 1:0 km=s through magnetic nanowire-waveguides (MNWs) have begun to attract considerable attention from the viewpoint of their promising applications for a new paradigm of logic devices [10]. In such devices, information signals can be generated by SW excitations from a local area, and then delivered by propagating SWs through MNWs, and finally manipulated via the superposition. However, the device conception of Ref.[10] assumes only small-amplitude SWs. The signal propagation in SW-based devices is much faster than in newly designed logic devices based on domain-wall propagation [11]. To make SWs applicable practically, it is thus crucially important to excite SWs with sufficiently large amplitudes from a local area like electromagnetic-wave radiation [12], as well as to confirm the fundamental wave behaviors of the SWs propagating along MNWs. In this letter, we report the finding of a simple, but novel and controllable method of reliable generation of strong SWs detectable as signals by using a MV core...

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Normal modes of spin excitations in magnetic nanoparticles

Cited by 74 publications

References 25 publications

Radiation of spin waves from magnetic vortex cores by their dynamic motion and annihilation processes

Radiation of spin waves from magnetic vortex cores by their dynamic motion and annihilation processes

Calculations of three-dimensional magnetic normal modes in mesoscopic permalloy prisms with vortex structure

Strong Radiation of Spin Waves by Core Reversal of a Magnetic Vortex and Their Wave Behaviors in Magnetic Nanowire Waveguides

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