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Beginning with a Heisenberg spin Hamiltonian for the manganese ions in the Mn_12 Ac molecule, we find a number of low-energy states of the system. We use these states to solve the time-dependent Schrodinger equation and find the…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Indranil Rudra , S. Ramasesha , Diptiman Sen

We use spin-lattice dynamics simulations to study the possibility of modeling the magnetic hysteresis behavior of a ferromagnetic material. The temporal evolution of the magnetic and mechanical degrees of freedom is obtained through a set…

Materials Science · Physics 2023-10-18 G. dos Santos , F. Romá , J. Tranchida , S. Castedo , L. F. Cugliandolo , E. M. Bringa

We present a general approach to the derivation of the effective anisotropy field which determines the dynamical behaviour of magnetic spins according to the Landau-Lifshitz-Gilbert equation. The approach is based on the gradient in…

Here we consider the magnetization dynamics in ferromagnetic nanoparticles or films driven by external magnetic field pulses directed transverse to the initial equilibrium state. The excitation pulse drives large-angle ultra-fast…

Dynamical Systems · Mathematics 2024-10-23 Alessandro Fortunati , Massimiliano d'Aquino , Claudio Serpico

By using the quantum kinetic approach with the instantaneous local equilibrium approximation, we propose an equation that is capable of addressing magnetization dynamics for a wide range of temperatures. The equation reduces to the…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Lei Xu , Shufeng Zhang

We successfully synthesize single crystals of the verdazyl radical $\alpha$-2,3,5-Cl$_3$-V. $Ab$ $initio$ molecular orbital calculations indicate that the two dominant antiferromagnetic interactions, $J_{\rm{1}}$ and $J_{\rm{2}}$ ($\alpha…

Strongly Correlated Electrons · Physics 2017-06-26 Hironori Yamaguchi , Yusuke Tamekuni , Yoshiki Iwasaki , Rei Otsuka , Yuko Hosokoshi , Takanori Kida , Masayuki Hagiwara

The ultra-fast magnetisation relaxation rates during the laser-induced magnetisation process are analyzed in terms of the Landau-Lifshitz-Bloch (LLB) equation for different values of spin $S$. The LLB equation is equivalent in the limit $S…

Materials Science · Physics 2015-05-20 U. Atxitia , O. Chubykalo-Fesenko

The longitudinal relaxation time of the magnetization of a system of two exchange coupled spins subjected to a strong magnetic field is calculated exactly by averaging the stochastic Gilbert-Landau-Lifshitz equation for the magnetization,…

Statistical Mechanics · Physics 2009-11-11 S. V. Titov , H. Kachkachi , Yu. P. Kalmykov , W. T. Coffey

We study the spin relaxation in an interacting two--dimensional electron gas in a strong magnetic field for the case that the electron density is close to filling just one Landau sub--level of one spin projection, i.e., for filling factor…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 W. Apel , Yu. A. Bychkov

With decreasing particle size, different mechanisms dominate the thermally activated magnetization reversal in ferromagnetic particles. We investigate some of these mechanisms for the case of elongated, single-domain nanoparticles which we…

Statistical Mechanics · Physics 2007-05-23 D. Hinzke , U. Nowak

We study the polariton relaxation dynamics for different scattering mechanisms as: Phonon and electron scattering procesess. The relaxation polariton is obtained at very short times by solving the Boltzman equation. Instead of the…

Other Condensed Matter · Physics 2009-11-11 F. Chaves , F. J. Rodriguez

Sharp structures in magnetic field-dependent spin Seebeck effect (SSE) voltages of Pt/Y$_{3}$Fe$_{5}$O$_{12}$ (YIG) at low temperatures are attributed to the magnon-phonon interaction. Experimental results are well reproduced by a Boltzmann…

Various types of mixed spin two-dimensional Heisenberg networks are investigated by means of Monte Carlo simulations. This study aims at interpreting quantitatively the thermodynamical properties of two-dimensional molecule-based magnets…

Statistical Mechanics · Physics 2009-10-30 B. Mombelli , O. Kahn , J. Leandri , Y. Leroyer , S. Mechkov , Y. Meurdesoif

Precise modeling of the magnetization dynamics of nanoparticles with finite size effects at fast varying temperatures is a computationally challenging task. Based on the Landau-Lifshitz-Bloch (LLB) equation we derive a coarse grained model…

Materials Science · Physics 2019-08-07 Christoph Vogler , Claas Abert , Florian Bruckner , Dieter Suess

We study the spin-phonon relaxation rate of both Kramers and non-Kramers molecular magnets in strongly diluted samples at low temperature. Using the "rotational" contribution to the spin-phonon Hamiltonian, universal formulae for the…

Strongly Correlated Electrons · Physics 2018-01-31 Le Tuan Anh Ho , Liviu F. Chibotaru

Temperature-dependent magnetic experiments like pump-probe measurements generated by a pulsed laser have become a crucial technique for switching the magnetization in the picosecond time scale. Apart from having practical implications on…

Spin relaxation between the two lowest-lying spin-states has been studied in the S=4 single molecule magnet Ni$_4$ under steady state conditions of low amplitude and continuous microwave irradiation. The relaxation rate was determined as a…

Mesoscale and Nanoscale Physics · Physics 2008-07-22 G. de Loubens , D. A. Garanin , C. C. Beedle , D. N. Hendrickson , A. D. Kent

Applying the method of characteristics leads to wavefunctions and dynamic localization conditions for electrons on the one dimensional lattice under perpendicular time dependent electric and magnetic fields. Such conditions proceed again in…

Mesoscale and Nanoscale Physics · Physics 2008-02-12 C. Micu , E. Papp , L. Aur

Energy dissipation via spin excitations is investigated for a hard ferromagnetic tip scanning a soft magnetic monolayer. We use the classical Heisenberg model with Landau-Lifshitz-Gilbert (LLG)-dynamics including a stochastic field…

Other Condensed Matter · Physics 2009-08-03 Martin P. Magiera , Lothar Brendel , Dietrich E. Wolf , Ulrich Nowak

Using zero temperature Monte Carlo simulations we have studied the magnetic hysteresis in a three-dimensional Ising model with nearest neighbor exchange and dipolar interaction. The average magnetization of spins located inside a sphere on…

Condensed Matter · Physics 2009-10-31 Gyorgy Szabo , Gyorgy Kadar