109 research outputs found
Microwave assisted magnetization reversal in single domain nanoelements
We studied the microwave assisted magnetic reversal of 65 nm by 71 nm
elliptical Ni80Fe20 nanomagnets. Hysteresis curves were measured by
magneto-optical Kerr effect for a range of microwave frequencies and
amplitudes. The coercive field Hc was reduced by 26% for an rf field of 0.08Hc
when the microwave frequency coincided with the minimum of the experimentally
determined ferromagnetic resonance frequency with varying dc field. The
experimental results for the fractional reduction in Hc with rf field amplitude
are in good agreement with numerical simulations for an array of interacting
macrospins with a physically realistic shape anisotropy distributio
Separation of the first- and second-order contributions in magneto-optic Kerr effect magnetometry of epitaxial FeMn/NiFe bilayers
The influence of second-order magneto-optic effects on Kerr effect
magnetometry of epitaxial exchange coupled FeMn/NiFe-bilayers is investigated.
A procedure for separation of the first- and second-order contributions is
presented. The full angular dependence of both contributions during the
magnetization reversal is extracted from the experimental data and presented
using gray scaled magnetization reversal diagrams. The theoretical description
of the investigated system is based on an extended Stoner-Wohlfarth model,
which includes an induced unidirectional and fourfold anisotropy in the
ferromagnet, caused by the coupling to the antiferromagnet. The agreement
between the experimental data and the theoretical model for both the first- and
second-order contributions are good, although a coherent reversal of the
magnetization is assumed in the model.Comment: 6 pages, 7 figures, submitted to J. Appl. Phy
Temperature dependent magnetization dynamics of magnetic nanoparticles
Recent experimental and theoretical studies show that the switching behavior
of magnetic nanoparticles can be well controlled by external time-dependent
magnetic fields. In this work, we inspect theoretically the influence of the
temperature and the magnetic anisotropy on the spin-dynamics and the switching
properties of single domain magnetic nanoparticles (Stoner-particles). Our
theoretical tools are the Landau-Lifshitz-Gilbert equation extended as to deal
with finite temperatures within a Langevine framework. Physical quantities of
interest are the minimum field amplitudes required for switching and the
corresponding reversal times of the nanoparticle's magnetic moment. In
particular, we contrast the cases of static and time-dependent external fields
and analyze the influence of damping for a uniaxial and a cubic anisotropy.Comment: accepted by Journal of Physics: Condensed Matte
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