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The amplification of astrophysical magnetic fields takes place via dynamo instability in turbulent environments. The presence of vorticity is crucial for the dynamo to happen. However, the role of vorticity is not yet fully understood. This…

Astrophysics of Galaxies · Physics 2024-12-11 Albert Elias-López , Fabio del Sordo , Daniele Viganò

We study the motion of a non-planar vortex in a circular easy-plane ferromagnet, which imitates a magnetic nanodot. Analysis was done using numerical simulations and a new collective variable theory which includes the coupling of…

Strongly Correlated Electrons · Physics 2007-05-23 Denis D. Sheka , Juan P. Zagorodny , Jean-Guy Caputo , Yuri Gaididei , Franz G. Mertens

We report the dynamic characterization of the spin-torque-driven in-plane precession modes of a spin-torque nano-oscillator based on two different synthetic ferrimagnets: a pinned one characterized by a strong RKKY interaction which is…

Mesoscale and Nanoscale Physics · Physics 2024-03-07 E. Monteblanco , F. Garcia-Sanchez , M. Romera , D. Gusakova , L. D. Buda-Prejbeanu , U. Ebels

We observe the dynamics of a single magnetic vortex in the presence of a random array of pinning sites. At low excitation amplitudes, the vortex core gyrates about its equilibrium position with a frequency that is characteristic of a single…

Materials Science · Physics 2009-11-11 R. L. Compton , P. A. Crowell

The frequency-dependent impedance is a fundamental property of electrical components. We show that it can be determined from the equilibrium dynamical fluctuations of the electrode charge in constant-potential molecular simulations,…

Chemical Physics · Physics 2023-03-15 Giovanni Pireddu , Benjamin Rotenberg

Using a magnetic resonance force microscope (MRFM), the power emitted by a spin transfer nano-oscillator consisting of a normally magnetized Py$|$Cu$|$Py circular nanopillar is measured both in the autonomous and forced regimes. From the…

Materials Science · Physics 2013-02-20 A. Hamadeh , Grégoire De Loubens , V. V. Naletov , J. Grollier , Ch. Ulysse , V. Cros , O. Klein

We have employed complete micromagnetic simulations to analyze dc current driven self-oscillations of a vortex core in a spin-valve nanopillar in a perpendicular field by including the coupled effect of the spin-torque and the magnetostatic…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 G. Finocchio , V. S. Pribiag , L. Torres , R. A. Buhrman , B. Azzerboni

We study frequency-dependent current noise through a single-level quantum dot connected to ferromagnetic leads with non-collinear magnetization. We propose to use the frequency-dependent Fano factor as a tool to detect single-spin dynamics…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Matthias Braun , Jürgen König , Jan Martinek

The switching process of the vortex core in a Permalloy nanodisk affected by a rotating magnetic field is studied theoretically. A detailed description of magnetization dynamics is obtained by micromagnetic simulations.

Strongly Correlated Electrons · Physics 2007-08-26 Volodymyr P. Kravchuk , Denis D. Sheka , Yuri Gaididei , Franz G. Mertens

The correlation of phase fluctuations in any type of oscillator fundamentally defines its spectral shape. However, in nonlinear oscillators, such as spin torque nano oscillators, the frequency spectrum can become particularly complex. This…

We derive the frequency of precession and conditions for stability for a quantized vortex in a single-component and a two-component Bose-Einstein condensate. The frequency of precession is proportional to the gradient of the free energy…

Soft Condensed Matter · Physics 2009-10-31 S. A. McGee , M. J. Holland

Fast and efficient switching of nanomagnets is one of the main challenges in the development of future magnetic memories. We numerically investigate the evolution of the static and dynamic spin wave (SW) magnetization in short (50-400 nm…

Mesoscale and Nanoscale Physics · Physics 2023-05-02 Diego Caso , Pablo Tuero , Javier Garcia , Konstantin Y. Guslienko , Farkhad G. Aliev

We present an experimental investigation of radial spin-wave modes in magnetic nano-disks with a vortex ground state. The spin-wave amplitude was measured using a frequency-resolved magneto optical network analyzer, allowing for…

Mesoscale and Nanoscale Physics · Physics 2015-06-23 M. Helsen , A. Gangwar , J. De Clercq , A. Vansteenkiste , B. Van Waeyenberge

We present an experimental and numerical study of three-magnon splitting in a micrometer-sized magnetic disk with the vortex state strongly deformed by static in-plane magnetic fields. Excited with a large enough power at frequency…

Mesoscale and Nanoscale Physics · Physics 2023-03-08 Lukas Körber , Christopher Heins , Ivan Soldatov , Rudolf Schäfer , Attila Kákay , Helmut Schultheiss , Katrin Schultheiss

The magnetic vortex core in a nanodot can be switched by an alternating transversal magnetic field. We propose a simple collective coordinate model which describes comprehensive vortex core dynamics, including resonant behavior, weakly…

Mesoscale and Nanoscale Physics · Physics 2020-07-23 Oleksandr V. Pylypovskyi , Denis D. Sheka , Volodymyr P. Kravchuk , Yuri Gaididei , Franz G. Mertens

Frequency modulation experiments were performed on a spin torque vortex oscillator for a wide range of modulation frequency, up to 10 % of the oscillator frequency. A thorough analysis of the intermodulation products shows that the key…

Mesoscale and Nanoscale Physics · Physics 2013-06-25 S. Y. Martin , C. Thirion , C. Hoarau , C. Baraduc , B. Diény

We investigate fundamental processes that govern dynamics of vortex nucleation in sub-100 nm mesoscopic magnets. We focus on a structure with broken symmetry - Pacman-like nanomagnet shape - in which we study micromagnetic behavior both by…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 Jaroslav Tobik , Vladimir Cambel , Goran Karapetrov

We present experimental, numerical, and theoretical evidence for a new mode of antiferromagnetic dynamics in nanoparticles. Elastic neutron scattering experiments on 8 nm particles of hematite display a loss of diffraction intensity with…

Strongly Correlated Electrons · Physics 2015-06-23 K. Lefmann , H. Jacobsen , J. Garde , P. Hedegard , A. Wischnewski , S. N. Ancona , H. S. Jacobsen , C. R. H. Bahl , L. Theil Kuhn

Assumption of certain hierarchy of soft ferromagnet energy terms, realized in small enough flat nano-elements, allows to obtain explicit expressions for their magnetization distributions. By minimising the energy terms sequentially, from…

Mesoscale and Nanoscale Physics · Physics 2010-09-01 Konstantin L. Metlov

This chapter describes spin-wave excitations in nanosized dots and rings in the presence of the vortex state. The special attention is paid to the manifestation of the competition between exchange and dipolar interactions in the spin-wave…

Mesoscale and Nanoscale Physics · Physics 2017-03-21 Sławomir Mamica