共查询到20条相似文献,搜索用时 31 毫秒
1.
A. M. Shutyĭ 《JETP Letters》2008,87(3):154-158
Bistable states in the precession dynamics of thin magnetic films with the stripe-domain structure have been investigated on the basis of a numerical solution of the equation of motion for magnetization. It has been found that weak additional perturbation due to chaotic and low-frequency harmonic oscillations of the magnetic field can substantially change the probability of the dynamical bistability regime and lead to the elimination of bistability establishing only one of the regimes. 相似文献
2.
The magnetization dynamics in (100) single-crystal films with a cubic anisotropy has been studied by numerical simulation.
It has been shown that the additional (bifurcation) resonance caused by the bistability, i.e., two closely spaced equilibrium
magnetization states, appears upon in-plane magnetization along the hard axis. The change in the resonance region and the
corresponding dynamic regimes with a variation in the RF field or with a small detuning of the magnetizing field has been
investigated. The regular and chaotic precession regimes near the bifurcation resonance have been revealed. The states of
dynamic bistability have been found. 相似文献
3.
A.?M.?Shuty? 《Physics of the Solid State》2010,52(7):1417-1423
A new type of stochastic resonance that arises between two precession modes under dynamic bistability conditions and is excited
by an alternating magnetic field, including a harmonic signal and a white noise, has been studied using a numerical analysis
of the uniform magnetization precession in a thin film. The spectrum of the steady-state dynamics of the system at stochastic
resonance has been investigated, and its distinctive features have been revealed for the longitudinal and transverse orientations
of the additional alternating field. 相似文献
4.
Tatiana M. Vasilevskaya Dmitriy I. SementsovAnatoliy M. Shutyi 《Journal of magnetism and magnetic materials》2012
We study low-frequency ferromagnetic resonance in a thin film magnetized along the hard magnetization axis performing an analysis of magnetization precession dynamics equations and numerical simulation. Two types of films are considered: polycrystalline uniaxial films and single-crystal films with cubic magnetic anisotropy. An additional (bifurcation) resonance initiated by the bistability, i.e. appearance of two closely spaced equilibrium magnetization states is registered. The modification of dynamic modes provoked by variation of the frequency, amplitude, and magnetic bias value of the ac field is studied. Both steady and chaotic magnetization precession modes are registered in the bifurcation resonance range. 相似文献
5.
To study the nonlinear dynamics of a uniformly precessing magnetization in perpendicularly magnetized (100) ferrite-garnet films, equations of motion are numerically solved over a wide ac field frequency range. Bifurcation changes in the magnetization precession and the states of dynamic bistability have been detected. The conditions of high-amplitude regular and stochastic dynamic regimes are revealed, and the possibilities of controlling these precession regimes by applied magnetic fields are shown. 相似文献
6.
The precession dynamics of the magnetization of a film with in-plane uniaxial anisotropy in the case of its biasing along
the hard magnetization axis has been analyzed by numerically solving the Landau-Lifshitz equations. It has been revealed that
the ferromagnetic resonance spectrum near the magnetic anisotropy field exhibits an additional peak, which is associated with
the angular bistability due to the presence of two symmetric angular equilibrium positions. The trajectories of precession
motion during biasing along the hard magnetization axis differ substantially from the trajectories corresponding to the biasing
along the easy axis. 相似文献
7.
A. M. Shutyi 《Technical Physics》2010,55(11):1577-1582
The average transient time of regular regimes corresponding to the dynamic bistability state is studied using analysis of
uniform precession of magnetization of a thin magnetic film. The possibility of controlling the transient process parameter
by an additional ac magnetic field in the form of a harmonic of noise signal is established. A new type of stochastic resonance
is detected, which corresponds to the probability of high-amplitude precession and is manifested during a short noise action. 相似文献
8.
The magnetic dynamic response function is studied in detail for systems in which the magnetization is conserved and is carried by the spin of one type of particle. Hydrodynamic equations for the magnetization in magnetic systems in the paramagnetic and ferromagnetic regimes in the absence of an external field are derived and are shown to be inapplicable when there is an external field present. The hydrodynamic forms of the response function are used to motivate general analytic expressions for the full dynamic response function. Some consideration is given to feasibility of observing the hydrodynamic regime in real systems. 相似文献
9.
H. Hauser D.C. Jiles Y. Melikhov L. Li R. Grssinger 《Journal of magnetism and magnetic materials》2006,300(2):273-283
The “law of approach to saturation” is a well-known mathematical model for describing the behavior of ferromagnets at high magnetic field strengths which has the additional advantage that it can be linked to anisotropy through one of the terms in the mathematical expression of the law. In this paper, two recent and more comprehensive models of the magnetization process are compared with the law of approach and with each other in terms of their capability to describe the dependence of the magnetization curve in the high field regime. The comparison leads to relations between these two models and the interpretation of certain aspects of the models in terms of anisotropy. It is shown that the effects of anisotropy can be incorporated directly into these models without any additional assumptions. 相似文献
10.
Investigation of scaling laws in frequency-dependent minor hysteresis loops for ferromagnetic steels
S. Kobayashi S. TsukidateY. Kamada H. KikuchiT. Ohtani 《Journal of magnetism and magnetic materials》2012,324(2):215-221
Scaling laws in dynamical magnetic minor hysteresis loops have been investigated in the magnetizing frequency range of 0.05-300 Hz for various steels including Cr-Mo-V steel subjected to creep, cold rolled steels, and plastically deformed Ni. Although scaling laws in the medium magnetization range found previously fail in the high magnetization frequency regime owing to a significant contribution of eddy currents, a scaling power law of the relation between remanence and remanence work of minor loops, associated with a constant exponent of approximately 1.9, holds true in a very low magnetization regime, irrespective of magnetization frequency and investigated materials. The coefficient of the law is proportionally related to Vickers hardness over the wide frequency range. These observations demonstrate that the scaling analysis of dynamical minor loops enables us to evaluate materials degradation in a short measurement time with low measurement field and high sensitivity to defect density. 相似文献
11.
R. De Renzi G. Allodi S. Fanesi G. Guidi F. Licci M. Hennion L. Pinsard 《Applied magnetic resonance》2000,19(3-4):421-430
We detected two spontaneous precession frequencies in antiferromagnetic pure LaMnO3, the end member of different families of charge-doped manganites. The muon site and local field orientation are identified for one frequency, which provides a measure of the staggered magnetization. We present additional zero and longitudinal field muon relaxation data on an LaMnO3.045 sample in which a new regime appears above an intermediate temperatureT*, where regions of magnetic order coexist with domains of fluctuating moments. These results are discussed in terms of nucleation of the ordered phase in a superparamagnetic matrix. 相似文献
12.
A. G. Isavnin 《Russian Physics Journal》2006,49(3):308-313
Theoretically, based on the approximation of discrete orientations, the effect of thermal stochastic resonance is considered
for a superparamagnetic particle with magnetic anisotropy of the “easy axis” type in view of an additional external permanent
magnetic field applied at an arbitrary angle relative to the easy magnetization axis. The dynamic susceptibility has been
calculated for a single-domain iron particle under the conditions of its modulation by a weak external radio-frequency field
at various absolute values and directions of the additional permanent magnetic field vector.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 67–71, March, 2006. 相似文献
13.
Dynamic regimes of a magnetic moment of 2 × 2, 3 × 3, and 4 × 4 square dipole lattices in the linearly and circularly polarized ac magnetic field and the perpendicular static field have been investigated. The possibility of regular and chaotic precession dynamics of the magnetic moment of the lattices has been demonstrated. A shift of the main magnetic resonance owing to the dipole–dipole interaction and additional resonances have been revealed. Quasiperiodic regimes and bistability states with a metastable chaotic attractor have been discovered. 相似文献
14.
15.
The dynamic behavior in the evolving pattern of thermally assisted, nonequilibrium domains in magnetic thin-film elements undergoing ultrafast 180 degrees magnetization reversal was studied. Magnetization reversal enters a fully dynamic regime when the external field conditions are changed much faster than the sample is able to respond. The dynamic pathway develops a complexity not seen in quasistatic reversal but still retains a high level of order with well-developed dynamic domain patterns formed in response to subnanosecond transitions of the external applied magnetic field. 相似文献
16.
V. L. Mironov A. A. Fraerman O. L. Ermolaeva 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(11):1475-1478
The effect of the probe field in a magnetic force microscope on the magnetization distribution in objects under study has been theoretically investigated. The perturbation of uniform magnetization state in thin ferromagnetic samples under the probe field was analyzed in the linear approximation. The additional contribution to the magnetic force microscope contrast caused by a local magnetic bias of the sample was calculated. 相似文献
17.
Nonlinear dynamics of a spherical magnetic particle and an ensemble of such particles in an external oscillating magnetic
field have been studied analytically and numerically in terms of the Landau-Lifshitz-Gilbert equation. The exact analytical
formulas have been obtained allowing the calculation of the projections of the mean-in-time magnetization of the system on
the frequency of an external field and initial orientation of magnetic moments. The behavior of the system in the limiting
cases of low and high frequencies has been considered. The analytical solutions obtained agree well with the direct numerical
calculations of the Landau-Lifshitz-Gilbert equation. The analytical theory of the effect of the nonlinear dynamic polarization
has been developed, and its applicability for designing devises of magnetic memory has been discussed. 相似文献
18.
A.?M.?Shuty? 《Journal of Experimental and Theoretical Physics》2010,110(2):243-252
Equilibrium states of different systems formed by coupled spherical bodies with dipole magnetic moments have been investigated
using a numerical analysis. The bistable states and the corresponding values of the net magnetic moment are determined for
a number of planar and three-dimensional systems of dipoles, and the conditions providing the existence of orientational configurations
of coupled dipoles involved in the bistability are analyzed. The disturbances of the magnetic moment due to the quasi-static
passage of an additional dipole and the dynamic modes excited by a homogeneous alternating magnetic field and represented
by periodic, quasi-periodic, and chaotic oscillations of the magnetic moment of the system are considered for several types
of systems. The bifurcation diagrams of the dynamic modes are constructed, and the specific features typical of the systems
under consideration are revealed. 相似文献
19.
T. M. Vasilevskaya D. I. Sementsov 《Journal of Experimental and Theoretical Physics》2010,110(5):754-758
The precession dynamics of the magnetization of a film with an in-plane uniaxial anisotropy is analyzed in the spectrum of
ferromagnetic resonance corresponding to magnetic biasing along the hard axis of the film. An additional resonance peak is
revealed near magnetic anisotropy field H
u
. This peak is related to the appearance of angular bistability due to the presence of two symmetric angular equilibrium positions
in field H < H
u
. 相似文献
20.
A contribution to electromagnetic power losses, additional to the losses due to eddy currents and exhibiting a resonance frequency
dependence with the main maximum near 1 GHz, has been observed for the ferromagnetic alloy Pd2AuFe in the frequency range 0.9 MHz–10 GHz in the absence of an external constant magnetic field. Investigations performed
in a dc magnetic field show that this effect is a natural ferromagnetic resonance due to intradomain magnetization precession
in the effective magnetic-anisotropy field.
Fiz. Tverd. Tela (St. Petersburg) 40, 1900–1904 (October 1998) 相似文献