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We theoretically investigate the role of spin fluctuations in charge transport through a magnetic junction. Motivated by recent experiments that measure a nonlinear dependence of the current on electrical bias, we develop a systematic…

Mesoscale and Nanoscale Physics · Physics 2019-02-06 Scott A. Bender , Rembert A. Duine , Yaroslav Tserkovnyak

The reorientation transition of the magnetization of ferromagnetic films is studied on a microscopic basis within Heisenberg spin models. Analytic expressions for the temperature dependent anisotropy are derived from which it is seen that…

Statistical Mechanics · Physics 2009-10-31 A. Hucht , K. D. Usadel

We discuss low-temperature properties of magnets with integer spin and large single-ion easy-plane anisotropy $D$ in transverse magnetic field $h$. Considering the exchange interaction between spins as a perturbation and using the diagram…

Strongly Correlated Electrons · Physics 2011-12-30 A. V. Sizanov , A. V. Syromyatnikov

We discuss numerical and theoretical results for models of magnetization switching in nanoparticles and ultrathin films. The models and computational methods include kinetic Ising and classical Heisenberg models of highly anisotropic…

Materials Science · Physics 2007-05-23 Per Arne Rikvold , Gregory Brown , Steven J. Mitchell , M. A. Novotny

We perform Monte Carlo simulations in a random anisotropy magnet at a intermediate exchange to anisotropy ratio. We focus on the out of equilibrium relaxation after a sudden quenching in the low temperature phase, well below the freezing…

Disordered Systems and Neural Networks · Physics 2009-11-11 Orlando V. Billoni , Sergio A. Cannas , Francisco A. Tamarit

Extensive Monte Carlo simulations are used to investigate the low-temperature properties of the random anisotropy Heisenberg model, which describes the magnetic behavior of amorphous rare-earth-transition metal alloy. We show that the…

Disordered Systems and Neural Networks · Physics 2009-11-10 M. Itakura

The two dimensional Spin-1 Blume-Capel ferromagnet is studied by Monte Carlo simulation with Metropolis algorithm. Starting from initial ordered spin configuration the reversal of magnetisation is investigated in presence of a magnetic…

Statistical Mechanics · Physics 2021-01-29 Moumita Naskar , Muktish Acharyya

We consider the effect of quantum spin fluctuations on the ground state properties of the Heisenberg antiferromagnet on an anisotropic triangular lattice using linear spin-wave theory. This model should describe the magnetic properties of…

Strongly Correlated Electrons · Physics 2009-10-31 J. Merino , Ross H. McKenzie , J. B. Marston , C. H. Chung

Magnetic properties of a tetrahedral "Ni_4" molecule are discussed in terms of the Heisenberg model, with magnetic anisotropy terms included, and on the basis of first-principle calculations within the density functional theory. It is shown…

Materials Science · Physics 2007-05-23 A. V. Postnikov , M. Brueger , J. Schnack

A common ploy to reduce the switching current and energy dissipation in spin-transfer-torque driven magnetization switching of shape-anisotropic single-domain nanomagnets is to employ magnets with low saturation magnetization $M_s$ and high…

Mesoscale and Nanoscale Physics · Physics 2011-12-06 Kuntal Roy , Supriyo Bandyopadhyay , Jayasimha Atulasimha , Kamaram Munira , Avik W. Ghosh

Electrically manipulating the quantum properties of nano-objects, such as atoms or molecules, is typically done using scanning tunnelling microscopes and lateral junctions. The resulting nanotransport path is well established in these model…

We propose a phenomenological model for incompressible magnetohydrodynamic turbulence. We argue that nonlinear-wave interaction weakens as the energy cascade proceeds to small scales, however, the anisotropy of fluctuations along the…

Astrophysics · Physics 2009-11-10 Stanislav Boldyrev

We investigate the influence of shape anisotropy on the magnetization reversal of a single-domain magnetic nanoparticle driven by a circularly polarized linear down-chirp microwave field pulse (DCMP). Based on the Landau-Lifshitz-Gilbert…

Mesoscale and Nanoscale Physics · Physics 2022-01-19 Z. K. Juthy , M. A. J. Pikul , M. A. S. Akanda , M. T. Islam

We calculate the anisotropy energy of a single-domain ferromagnetic particle in which the only source of anisotropy is the presence of non-magnetic impurities. We find that such anisotropy takes the form of combined easy-axis and easy-plane…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Piet W. Brouwer , Denis A. Gorokhov

The Heisenberg model on a triangular lattice is a prime example for a geometrically frustrated spin system. However most experimentally accessible compounds have spatially anisotropic exchange interactions. As a function of this anisotropy,…

Strongly Correlated Electrons · Physics 2014-05-05 Burkhard Schmidt , Peter Thalmeier

Analytical solution has been found for the second-order effective anisotropy of magnetic nanoparticles of a cubic shape due to the surface anisotropy (SA) of the N\'eel type. Similarly to the spherical particles, for the simple cubic…

Mesoscale and Nanoscale Physics · Physics 2018-09-12 D. A. Garanin

We simulate the spin torque-induced reversal of the magnetization in thin disks with perpendicular anisotropy at zero temperature. Disks typically smaller than 20 nm in diameter exhibit coherent reversal. A domain wall is involved in larger…

Mesoscale and Nanoscale Physics · Physics 2018-12-03 Paul Bouquin , Siddharth Rao , Gouri Sankar Kar , Thibaut Devolder

The conductance of a ferromagnetic particle depends on the relative orientation of the magnetization with respect to the direction of current flow. This phenomenon is known as "anisotropic magnetoresistance". Quantum interference leads to…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Shaffique Adam , Markus Kindermann , Saar Rahav , Piet W. Brouwer

The magnetization reversal rate via thermal creation of soliton pairs in quasi-1D ferromagnetic systems is calculated. Such a model describes e.g. the time dependent coercivity of elongated particles as used in magnetic recording media. The…

Condensed Matter · Physics 2009-10-22 Hans-Benjamin Braun

Operation parameters of magnetic quantum cellular automata are evaluated for the purposes of reliable logic operation. The dynamics of the nanomagnets is simulated via the Landau-Lifshitz-Gilbert equations with a stochastic magnetic field…

Mesoscale and Nanoscale Physics · Physics 2009-06-30 Federico M. Spedalieri , Ajey P. Jacob , Dmitri Nikonov , Vwani P. Roychowdhury