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We consider the heat equation in a straight strip, subject to a combination of Dirichlet and Neumann boundary conditions. We show that a switch of the respective boundary conditions leads to an improvement of the decay rate of the heat…

偏微分方程分析 · 数学 2011-02-21 David Krejcirik , Enrique Zuazua

An excitation of highly nonlinear, complex magnetization dynamics in a ferromagnet, for example chaos, is a new research target in spintronics. This technology is applied to practical applications such as random number generator and…

介观与纳米尺度物理 · 物理学 2024-06-11 Tomohiro Taniguchi

We have used Monte Carlo simulations to investigate the magnetic properties of asymmetric dots as a function of their geometry. The asymmetry of round dots is produced by cutting off a fraction of the dot and is characterized by an…

介观与纳米尺度物理 · 物理学 2011-06-08 N. M. Vargas , S. Allende , B. Leighton , J. Escrig , J. Mejía-López , D. Altbir , Ivan K. Schuller

Using an effective Hamiltonian including the Zeeman and internal interactions, we describe the quantum theory of magnetization dynamics when the spin system evolves non-adiabatically and out of equilibrium. The Lewis-Riesenfeld dynamical…

其他凝聚态物理 · 物理学 2008-11-26 F. M. Saradzhev , F. C. Khanna , Sang Pyo Kim , M. de Montigny

We use the density matrix renormalization group method (DMRG) to compute the frequency and momentum resolved spin-spin correlation functions of a dimerized spin-1/2 chain under a magnetic field at finite temperature. The spectral features…

强关联电子 · 物理学 2018-10-09 Emanuele Coira , Peter Barmettler , Thierry Giamarchi , Corinna Kollath

One of the fundamental effects of the laser-matter interaction is the appearance of an induced transient magnetisation. While the underlying phenomena differ in their microscopic origin and cover a diverse array of materials, here we…

介观与纳米尺度物理 · 物理学 2023-09-26 Paul-Iulian Gavriloaea , Elías Saugar , Rubén Otxoa , Oksana Chubykalo-Fesenko

We review work by the authors on thermal activation in nanoscopic magnetic systems. These systems present unique difficulties in analyzing noise-induced escape over a barrier, including the presence of nonlocal interactions, nongradient…

介观与纳米尺度物理 · 物理学 2023-01-11 Gabriel D. Chaves-O'Flynn , D. L. Stein

With Monte Carlo methods we study the dynamic relaxation of a vortex state at the Kosterlitz-Thouless phase transition of the two-dimensional XY model. A local pseudo-magnetization is introduced to characterize the symmetric structure of…

计算物理 · 物理学 2012-02-01 X. P. Qin , B. Zheng , N. J. Zhou

We comment on some misleading and biased statements appearing in the manuscript arXiv:1209.0298 ("Thermal fluctuations of magnetic nanoparticles") about the use of the damped Landau-Lifshitz equation and the kinetic Langer theory for the…

介观与纳米尺度物理 · 物理学 2012-10-10 J. -L. Déjardin , H. Kachkachi , J. -M. Martinez

Far-from-equilibrium magnetization dynamics can be accessed when a magnetic material is subject to a femtosecond excitation, such as an optical laser or an electric current. Numerically, the demagnetization of magnetic materials is…

介观与纳米尺度物理 · 物理学 2026-03-10 Ezio Iacocca

The deterministic Landau-Lifshitz-Gilbert equation has been used to investigate the nonlinear dynamics of magnetization and the specific loss power in magnetic nanoparticles with uniaxial anisotropy driven by a rotating magnetic field,…

介观与纳米尺度物理 · 物理学 2012-12-13 I. Nandori , J. Racz

By applying a variational principle on a magnetic system within the framework of extended irreversible thermodynamics, we find that the presence of a temperature gradient in a ferromagnet leads to a generalisation of the Landau-Lifshitz…

材料科学 · 物理学 2015-10-12 Sylvain D. Brechet , Jean-Philippe Ansermet

We formulate the statistical dynamics of topological defects in the active nematic phase, formed in two dimensions by a collection of self-driven particles on a substrate. An important consequence of the non-equilibrium drive is the…

软凝聚态物质 · 物理学 2018-09-12 Suraj Shankar , Sriram Ramaswamy , M. Cristina Marchetti , Mark J. Bowick

We investigate weakly coupled spin-1/2 ladders in a magnetic field. The work is motivated by recent experiments on the compound $\mathrm{(C_5H_{12}N)_2CuBr_4}$ (BPCB). We use a combination of numerical and analytical methods, in particular…

强关联电子 · 物理学 2012-01-26 Pierre Bouillot

We study the influence of thermal fluctuations on the magnetic behavior of square mesoscopic superconductors. The strength of thermal fluctuations are parameterized using the Ginzburg number, which is small ($G_i \approx 10^{-10}$) in…

超导电性 · 物理学 2009-11-11 Alexander D. Hernandez , B. J. Baelus , Daniel Dominguez , F. M. Peeters

We report a full (3D) micromagnetic simulation of a set of 100 ferrite (Fe$_3$O$_4$) cylindrical dots, arranged in a 10 by 10 square (planar) array of side 3.27 $\mu$m, excited by an external in-plane magnetic field. The resulting power…

介观与纳米尺度物理 · 物理学 2012-01-20 Christine C. Dantas

Possibility of flat-band ferromagnetism in quantum dot arrays is theoretically discussed. By using a quantum dot as a building block, quantum dot superlattices are possible. We consider dot arrays on Lieb and kagome lattices known to…

强关联电子 · 物理学 2009-11-07 Hiroyuki Tamura , Kenji Shiraishi , Takashi Kimura , Hideaki Takayanagi

We investigate the effect of temperature on the dynamic properties of magnetic vortices in small disks. Our calculations use a stochastic version of the Landau-Lifshitz-Gilbert (LLG) equation, valid for finite temperatures well below the…

介观与纳米尺度物理 · 物理学 2012-07-11 Tiago S. Machado , Tatiana G. Rappoport , Luiz C. Sampaio

We consider the coupled system of the Landau--Lifshitz--Gilbert equation and the conservation of linear momentum law to describe magnetic processes in ferromagnetic materials including magnetoelastic effects in the small-strain regime. For…

数值分析 · 数学 2025-01-15 Hywel Normington , Michele Ruggeri

In this paper, Landau diamagnetism is revisited in the context of nonextensive statistical thermodynamics. Exact as well as approximate expressions for partition function, magnetization and susceptibility are obtained by using Hilhorst…

统计力学 · 物理学 2007-05-23 I. Sokmen , F. Buyukkilic , D. Demirhan