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A micromagnetic numerical study of the precessional motion of the vortex and antivortex states in soft ferromagnetic circular nanodots is presented using Landau-Lifshitz-Gilbert dynamics. For sufficiently small dot thickness and diameter,…

Materials Science · Physics 2012-03-28 Andreas Lyberatos , Stavros Komineas , Nikos Papanicolaou

The formation of quantized vortices in trapped, gaseous Bose-Einstein condensates is considered. The thermodynamic stability of vortex states and the essential role of the surface excitations as a route for vortex penetration into the…

Soft Condensed Matter · Physics 2008-07-10 T. P. Simula , S. M. M. Virtanen , M. M. Salomaa

We study the Landau-Lifshitz-Gilbert equation for the dynamics of a magnetic vortex system. We present a PDE-based method for proving vortex dynamics that does not rely on strong well-preparedness of the initial data and allows for…

Analysis of PDEs · Mathematics 2012-03-21 Matthias Kurzke , Christof Melcher , Roger Moser , Daniel Spirn

Magnetic platelets with a vortex configuration are attracting considerable attention. The discovery that excitation with small in-plane magnetic fields or spin polarised currents can switch the polarisation of the vortex core did not only…

We study the magnetization dynamics in a nanocontact magnetic vortex oscillators as function of temperature. Low temperature experiments reveal that the dynamics at low and high currents differ qualitatively. At low currents, we excite a…

It is crucially important to investigate effects of temperature on magnetic properties such as critical phenomena, nucleation, pinning, domain wall motion, coercivity, etc. The Landau-Lifshitz-Gilbert (LLG) equation has been applied…

Materials Science · Physics 2015-07-14 Masamichi Nishino , Seiji Miyashita

We theoretically study the oscillatory dynamics of a vortex core in a ferrimagnetic disk near its angular momentum compensation point, where the spin density vanishes but the magnetization is finite. Due to the finite magnetostatic energy,…

Mesoscale and Nanoscale Physics · Physics 2017-07-19 Se Kwon Kim , Yaroslav Tserkovnyak

We study the effects of finite temperature on the dynamics of non-planar vortices in the classical, two-dimensional anisotropic Heisenberg model with XY- or easy-plane symmetry. To this end, we analyze a generalized Landau-Lifshitz equation…

We investigate the vortex excitations induced by a spin-polarized current in a magnetic nanopillar by means of micromagnetic simulations and analytical calculations. Damped motion, stationary vortex rotation and the switching of the vortex…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 A. V. Khvalkovskiy , J. Grollier , A. Dussaux , K. A. Zvezdin , V. Cros

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

We studied the temperature dependence of the magnetization reversal in individual submicron permalloy disks with micro-Hall and bend-resistance magnetometry. The nucleation field exhibits a nonmonotonic dependence with positive and negative…

Mesoscale and Nanoscale Physics · Physics 2010-03-17 G. Mihajlovic , M. S. Patrick , J. E. Pearson , V. Novosad , S. D. Bader , M. Field , G. J. Sullivan , A. Hoffmann

The magnetic behavior of bcc iron nanoclusters, with diameters between 2 and 8 nm, is investigated by means of spin dynamics (SD) simulations coupled to molecular dynamics (MD-SD), using a distance-dependent exchange interaction.…

Mesoscale and Nanoscale Physics · Physics 2020-11-25 G. Dos Santos , R. Aparicio , D. Linares , E. N. Miranda , J. Tranchida , G. M. Pastor , E. M. Bringa

Laser-induced demagnetization is theoretically studied by explicitly taking into account interactions among electrons, spins and lattice. Assuming that the demagnetization processes take place during the thermalization of the sub-systems,…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 A. Manchon , Q. Li , L. Xu , S. Zhang

We study the dynamics of a single and a pair of vortices in quasi two-dimensional Bose-Einstein condensates at finite temperatures. We use the stochastic Gross-Pitaevskii equation, which is the Langevin equation for the Bose-Einstein…

Quantum Gases · Physics 2014-02-04 S. Gautam , Arko Roy , Subroto Mukerjee

We have numerically investigated the dynamics of vortices in a clean layered superconductor placed in a perpendicular magnetic field. We describe the energetics using a Ginzburg-Landau free energy functional in the lowest Landau level…

Superconductivity · Physics 2007-05-23 W. A. Al-Saidi , D. Stroud

We use Monte Carlo simulations to study the finite temperature behavior of vortices in the XY- model for tangent vector order on curved backgrounds. Contrary to naive expectations, we show that the underlying geometry does not affect the…

Statistical Mechanics · Physics 2018-01-24 Leopoldo R. Gómez , Nicolás A. García , Daniel A. Vega , José Lorenzana

The microscopic mechanism of thermal dissipation in quantum turbulence has been numerically studied by solving the coupled system involving the Gross-Pitaevskii equation and the Bogoliubov-de Gennes equation. At low temperatures, the…

Disordered Systems and Neural Networks · Physics 2009-11-11 Michikazu Kobayashi , Makoto Tsubota

By numerical and analytical methods, we study in detail the effects of the Lifshitz dynamical exponent $z$ on the vector condensate induced by an applied magnetic field in the probe limit. Concretely, in the presence of the magnetic field,…

High Energy Physics - Theory · Physics 2014-05-20 Ya-Bo Wu , Jun-Wang Lu , Mo-Lin Liu , Jian-Bo Lu , Cheng-Yuan Zhang , Zhuo-Qun Yang

Numerical integration of a stochastic Landau-Lifshitz-Gilbert equation is used to study dynamic processes in single-domain nanoscale magnets at nonzero temperatures. Special attention is given to including thermal fluctuations as a Langevin…

Materials Science · Physics 2009-10-31 Gregory Brown , M. A. Novotny , Per Arne Rikvold

We study the finite temperature properties of quantum magnets close to a continuous quantum phase transition between two distinct valence bond solid phases in two spatial dimension. Previous work has shown that such a second order quantum…

Strongly Correlated Electrons · Physics 2009-11-10 Pouyan Ghaemi , Ashvin Vishwanath , T. Senthil