Search results for "Magnetostatics"
showing 10 items of 28 documents
Switching the Magnetic Vortex Core in a Single Nanoparticle.
2016
Imaging and manipulating the spin structure of nano- and mesoscale magnetic systems is a challenging topic in magnetism, yielding a wide range of spin phenomena such as skyrmions, hedgehog-like spin structures, or vortices. A key example has been provided by the vortex spin texture, which can be addressed in four independent states of magnetization, enabling the development of multibit magnetic storage media. Most of the works devoted to the study of the magnetization reversal mechanisms of the magnetic vortices have been focused on micrometer-size magnetic platelets. Here we report the experimental observation of the vortex state formation and annihilation in individual 25 nm molecular-bas…
Manipulating antiferromagnets with magnetic fields: Ratchet motion of multiple domain walls induced by asymmetric field pulses
2016
Future applications of antiferromagnets (AFs) in many spintronics devices rely on the precise manipulation of domain walls. The conventional approach using static magnetic fields is inefficient due to the low susceptibility of AFs. Recently proposed electrical manipulation with spin-orbit torques is restricted to metals with a specific crystal structure. Here we propose an alternative, broadly applicable approach: using asymmetric magnetic field pulses to induce controlled ratchet motion of AF domain walls. The efficiency of this approach is based on three peculiarities of AF dynamics. First, a time-dependent magnetic field couples with an AF order parameter stronger than a static magnetic …
Gyrotron interaction simulations with tapered magnetostatic field
2010
We investigate the interaction of the electron beam with the RF wave in a gyrotron, in the presence of an axially tapered magnetic field. The simulation results of three interaction codes are compared and the different modelings are discussed.
Automotive domain wall propagation in ferromagnetic rings
2015
Automotive domain wall propagation is a self-propelling motion utilizing the energy stored in a particular energy reservoir of the spin structure to speed up domain wall beyond its equilibrium value given by external driving force and damping. Such a concept of DW motion is of great interest due to recent development of spintronic devices based on domain walls, where automotion could be used to assist or prevent domain wall pinning at low driving fields1-2. In turn, most of studies so far have been devoted to the automotion invoked by DW transformations from metastable to stable states3-4; appearing at sufficiently high magnetic fields strong and enough to trigger domain wall spin structure…
Coherent Spin Dependent Landau-Zener Tunneling in Mixed Valence Dimers
2011
In this contribution we introduce the concept of single molecule ferroelectric based on the vibronic pseudo Jahn-Teller model of mixed valence dimeric clusters belonging to the Robin and Day class II compounds. We elucidate the main factors controlling the nonadiabatic Landau-Zener tunneling between the low lying vibronic levels induced by a pulse of the electric field. The transition probabilities are shown to be dependent on the both time of the pulse and the total spin of the cluster. A possibility to control the spin-dependent Landau-Zener tunneling by applying a static magnetic field is discussed.
Design of a System to Compose 50 Hz Alternating and Static Magnetic Field From Induction Coil and Permanent Magnets
2020
We demonstrate a technical solution to achieve an intense 50 Hz alternating magnetic field and a static magnetic field made by a permanent magnet at the same place. A compact coil built using the Bitter coil concept is customized to support alternating current, thus creating an alternating magnetic field. A complementary permanent magnet assembly is built around it to achieve the superposition of both fields along the axis of symmetry. Results from the experimental model are compared to both numerical and analytical models.
Stability analysis of an electromagnetically levitated sphere
2006
We present a combined numerical and analytical approach to analyze the static and dynamic stabilities of an electromagnetically levitated spherical body depending on the ac frequency and the configuration of a three-dimensional (3D) coil made of thin winding which is modeled by linear current filaments. First, we calculate numerically the magnetic vector potential in grid points on the surface of the sphere and then use Legendre and fast Fourier transforms to find the expansion of the magnetic field in terms of spherical harmonics. Second, we employ a previously developed gauge transformation to solve analytically the 3D electromagnetic problem in terms of the numerically obtained expansion…
Simulation of forces and 3-D field arising during power autotransformer fault due to electric arc in HV winding
2002
Forces and three-dimensional magnetic fields in high-voltage winding due to an internal short circuit in a power autotransformer are calculated with the computer package OPERA 3D. The considered damage was caused by an electric arc. The materialized deformation of the winding part confirms the simulation results.
Polarimetry on dense samples of spin-polarized 3He by magnetostatic detection
1997
Abstract A very sensitive low-field fluxgate magnetometer is used to detect the static magnetic field produced by dense samples of spin-polarized 3He gas contained in spherical glass cells at pressures around several bars. The 3He nuclear polarization can be extracted with high precision ΔP P by utilizing magnetostatic detection in combination with adiabatic fast-passage spin reversal. The polarization losses can be kept well below 0.1% thus making this type of polarimetry almost non-destructive. More simply even, P can be measured with reduced accuracy by the change of field when the cell is removed from the fluxgate. In this case the accuracy is limited to about 10% due to the uncertainti…
Analysis of equations arising in gyrotron theory
2012
The gyrotron is a microwave source whose operation is based on the stimulated cyclotron radiation of electrons oscillating in a static magnetic field. Powerful gyrotrons can be used to heat nuclear fusion plasma. In addition, they have found a wide utility in plasma diagnostics, plasma chemistry, radars, extra-high-resolution spectroscopy, high-temperature processing of materials, medicine, etc. However, the main application of gyrotrons is in electron cyclotron resonance heating in tokamaks and stellarators. Equations describing gyrotron operation are ordinary differential equations and Schrödinger type partial differential equations. The present paper provides a survey of the analytical a…