66 research outputs found
Dynamics of ferromagnetic nanomagnets with vortex or single-domain configuration
We study the dynamics of flat circular permalloy nanomagnets for 1.) magnetic
vortex and 2.) single-domain configurations, using micromagnetic simulation.
Dynamical studies for isolated vortex structures show that both the vorticity
and the central polarity of the out-of-plane component can be switched fast
(50-100 ps) and independently. Micromagnetic simulations of the switching
process in thin cylindrical Permalloy (Py) nanoparticles with an initial stable
single-domain state show nearly homogeneous single-domain behaviour followed by
excitation of spin waves.Comment: 2 pages with 3 eps-figures, --> ICM2003 Rome 28.7.-1.8.03, --> JMM
Influence of point defects on magnetic vortex structures
We employed micro-Hall magnetometry and micromagnetic simulations to
investigate magnetic vortex pinning at single point defects in individual
submicron-sized permalloy disks. Small ferromagnetic particles containing
artificial point defects can be fabricated by using an image reversal electron
beam lithography process. Corresponding micromagnetic calculations, modeling
the defects within the disks as holes, give reasonable agreement between
experimental and simulated pinning and depinning field values
Shifting and pinning of a magnetic vortex core in a permalloy dot by a magnetic field
Magnetic pinning in thin films seems to be a major research subject in the near future, as it is involved in all switching processes which include a movement of a domain wall or a magnetic vortex. We used Lorentz transmission electron microscopy and vortex pinning at artificial pinning sites to investigate the pinning behavior of magnetic vortices for the first time with high spatial resolution
The Acceleration and Storage of Radioactive Ions for a Beta-Beam Facility
The term beta-beam has been coined for the production of a pure beam of
electron neutrinos or their antiparticles through the decay of radioactive ions
circulating in a storage ring. This concept requires radioactive ions to be
accelerated to as high Lorentz gamma as 150. The neutrino source itself
consists of a storage ring for this energy range, with long straight sections
in line with the experiment(s). Such a decay ring does not exist at CERN today,
nor does a high-intensity proton source for the production of the radioactive
ions. Nevertheless, the existing CERN accelerator infrastructure could be used
as this would still represent an important saving for a beta-beam facility.Comment: beta-beam working group website at http://cern.ch/beta-bea
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