258 research outputs found
Generation of pulse trains by current-controlled magnetic mirrors
The evolution of a spin-wave packet trapped between two direct
current-carrying wires placed on the surface of a ferrite film is observed by
Brillouin light scattering. The wires act as semi-transparent mirrors confining
the packet. Because the spin-wave energy partially passes through these
mirrors, trains of spin-wave packets are generated outside the trap. A
numerical model of this process is presented and applied to the case when the
current in the wires is dynamically controlled. This dynamical control of the
mirror reflectivity provides new functionalities interesting for the field of
spin-wave logic like that of a spin-wave memory cell.Comment: 4 pages, 3 figure
Formation of guided spin-wave bullets in ferrimagnetic film stripes
The formation of quasi-2D nonlinear spin-wave eigenmodes in longitudinally
magnetized stripes of a ferrimagnetic film, so-called guided spin-wave bullets,
was experimentally observed by using time- and space-resolved Brillouin light
scattering spectroscopy and confirmed by numerical simulation. They represent
stable spin-wave packets propagating along a waveguide structure, for which
both transversal instability and interaction with the side edges of the
waveguide are important. The experiments and the numerical simulation of the
evolution of the spin-wave excitations show that the shape of the formed
packets and their behavior are strongly influenced by the confinement
conditions. The discovery of these modes demonstrates the existence of
quasi-stable nonlinear solutions in the transition regime between
one-dimensional and two-dimensional wave packet propagation.Comment: 4 pages, 3 figure
Phase sensitive Brillouin scattering measurements with a novel magneto-optic modulator
A recently reported phase sensitive Brillouin light scattering technique is
improved by use of a magnetic modulator. This modulator is based on Brillouin
light scattering in a thin ferrite film. Using this magnetic modulator in time-
and space Brillouin light scattering measurements we have increased phase
contrast and excluded influence of optical inhomogeneities in the sample. We
also demonstrate that the quality of the resulting interference patterns can be
improved by data postprocessing using the simultaneously recorded information
about the reference light
Scattering of backward spin waves in a one-dimensional magnonic crystal
Scattering of backward volume magnetostatic spin waves from a one-dimensional
magnonic crystal, realized by a grating of shallow grooves etched into the
surface of an yttrium-iron garnet film, was experimentally studied. Rejection
frequency bands were clearly observed. The rejection efficiency and the
frequency width of the rejection bands increase with increasing groove depth. A
theoretical model based on the analogy of a spin-wave film-waveguide with a
microwave transmission line was used to interpret the obtained experimental
results.Comment: 4 pages, 3 figure
Magnonic crystal based forced dominant wavenumber selection in a spin-wave active ring
Spontaneous excitation of the dominant mode in a spin-wave active ring -- a
self-exciting positive-feedback system incorporating a spin-wave transmission
structure -- occurs at a certain threshold value of external gain. In general,
the wavenumber of the dominant mode is extremely sensitive to the properties
and environment of the spin-wave transmission medium, and is almost impossible
to predict. In this letter, we report on a backward volume magnetostatic
spin-wave active ring system incorporating a magnonic crystal. When mode
enhancement conditions -- readily predicted by a theoretical model -- are
satisfied, the ring geometry permits highly robust and consistent forced
dominant wavenumber selection.Comment: 4 pages, 3 figure
Low-damping transmission of spin waves through YIG/Pt-based layered structures for spin-orbit-torque applications
We show that in YIG-Pt bi-layers, which are widely used in experiments on the
spin transfer torque and spin Hall effects, the spin-wave amplitude
significantly decreases in comparison to a single YIG film due to the
excitation of microwave eddy currents in a Pt coat. By introducing a novel
excitation geometry, where the Pt layer faces the ground plane of a microstrip
line structure, we suppressed the excitation of the eddy currents in the Pt
layer and, thus, achieved a large increase in the transmission of the
Damon-Eshbach surface spin wave. At the same time, no visible influence of an
external dc current applied to the Pt layer on the spin-wave amplitude in the
YIG-Pt bi-layer was observed in our experiments with YIG films of micrometer
thickness
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