Journal ArticleDOI
Langevin-dynamics study of the dynamical properties of small magnetic particles
TLDR
In this paper, the Langevin-dynamics approach was used to study the dynamics of magnetic nanoparticles, and the results were compared with different analytical expressions used to model the relaxation of nanoparticle ensembles, assessing their accuracy.Abstract:
The stochastic Landau-Lifshitz-Gilbert equation of motion for a classical magnetic moment is numerically solved (properly observing the customary interpretation of it as a Stratonovich stochastic differential equation), in order to study the dynamics of magnetic nanoparticles. The corresponding Langevin-dynamics approach allows for the study of the fluctuating trajectories of individual magnetic moments, where we have encountered remarkable phenomena in the overbarrier rotation process, such as crossing-back or multiple crossing of the potential barrier, rooted in the gyromagnetic nature of the system. Concerning averaged quantities, we study the linear dynamic response of the archetypal ensemble of noninteracting classical magnetic moments with axially symmetric magnetic anisotropy. The results are compared with different analytical expressions used to model the relaxation of nanoparticle ensembles, assessing their accuracy. It has been found that, among a number of heuristic expressions for the linear dynamic susceptibility, only the simple formula proposed by Shliomis and Stepanov matches the coarse features of the susceptibility reasonably. By comparing the numerical results with the asymptotic formula of Storonkin {Sov. Phys. Crystallogr. 30, 489 (1985) [Kristallografiya 30, 841 (1985)]}, the effects of the intra-potential-well relaxation modes on the low-temperature longitudinal dynamic response have been assessed, showing their relatively small reflection in the susceptibility curves but their dramatic influence on the phase shifts. Comparison of the numerical results with the exact zero-damping expression for the transverse susceptibility by Garanin, Ishchenko, and Panina {Theor. Math. Phys. (USSR) 82, 169 (1990) [Teor. Mat. Fiz. 82, 242 (1990)]}, reveals a sizable contribution of the spread of the precession frequencies of the magnetic moment in the anisotropy field to the dynamic response at intermediate-to-high temperatures.read more
Citations
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Journal ArticleDOI
Description of a dissipative quantum spin dynamics with a Landau-Lifshitz/Gilbert like damping and complete derivation of the classical Landau-Lifshitz equation
TL;DR: In this paper, a time dependent Schrodinger equation corresponding to the classical Landau-Lifshitz-Gilbert equation and two ways to include temperature into the quantum mechanical spin dynamics have been proposed.
Book ChapterDOI
Characterization of Resovist® Nanoparticles for Magnetic Particle Imaging
Takashi Yoshida,Keiji Enpuku,Frank Ludwig,Jan Dieckhoff,Thilo Wawrzik,Aidin Lak,Meinhard Schilling +6 more
TL;DR: In this paper, the dynamic magnetic properties of Resovist® for magnetic particle imaging (MPI) utilizing static M-H, ac susceptibility (ACS), and magnetic particle spectroscopy (MPS) measurements were investigated.
Journal ArticleDOI
Numerical investigation of spin-torque using the Heisenberg model
TL;DR: In this paper, the authors present numerical calculations of the spin transfer torque resulting in current-induced domain wall motion using an atomistic/classical Heisenberg spin model approach, which is well suited to study geometrically confined domain walls.
Journal ArticleDOI
AC susceptibility as a tool to probe the dipolar interaction in magnetic nanoparticles
Gabriel T. Landi,Fabiana R. Arantes,Daniel Reinaldo Cornejo,Andris F. Bakuzis,Irene Andreu,Eva Natividad +5 more
TL;DR: In this article, the authors show how AC susceptibility may be used to obtain information regarding the influence of the dipolar interaction in a sample, which is particularly important when the particles are kept in a fluid suspension or packed within nano-carriers.
Journal ArticleDOI
Anisotropic magnetic molecular dynamics of cobalt nanowires
TL;DR: In this paper, a spin-pair model of anisotropy is proposed to connect to the lattice thermodynamics, and the efficiencies of algorithms based on SuzukiTrotterdecompositions are compared.
References
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Journal ArticleDOI
Handbook of Mathematical Functions
Book
Stochastic processes in physics and chemistry
TL;DR: In this article, the authors introduce the Fokker-planck equation, the Langevin approach, and the diffusion type of the master equation, as well as the statistics of jump events.
Stochastic Processes in Physics and Chemistry
Abstract: Preface to the first edition. Preface to the second edition. Abbreviated references. I. Stochastic variables. II. Random events. III. Stochastic processes. IV. Markov processes. V. The master equation. VI. One-step processes. VII. Chemical reactions. VIII. The Fokker-Planck equation. IX. The Langevin approach. X. The expansion of the master equation. XI. The diffusion type. XII. First-passage problems. XIII. Unstable systems. XIV. Fluctuations in continuous systems. XV. The statistics of jump events. XVI. Stochastic differential equations. XVII. Stochastic behavior of quantum systems.
Book
Numerical Solution of Stochastic Differential Equations
Peter E. Kloeden,Eckhard Platen +1 more
TL;DR: In this article, a time-discrete approximation of deterministic Differential Equations is proposed for the stochastic calculus, based on Strong Taylor Expansions and Strong Taylor Approximations.