49 research outputs found
Influence of nonmagnetic dielectric spacers on the spin wave response of one-dimensional planar magnonic crystals
The one-dimensional planar magnonic crystals are usually fabricated as a
sequence of stripes intentionally or accidentally separated by non-magnetic
spacers. The influence of spacers on shaping the spin wave spectra is complex
and still not completely clarified. We performed the detailed numerical studies
of the one-dimensional single- and bi-component magnonic crystals comprised of
a periodic array of thin ferromagnetic stripes separated by non-magnetic
spacers. We showed that the dynamic dipolar interactions between the stripes
mediated by non-magnetic spacer, even ultra-narrow, significantly shift up the
frequency of the ferromagnetic resonance and simultaneously reduce the spin
wave group velocity, which is manifested by the flattening of the magnonic
band. We attributed these changes in the spectra to the modifications of
dipolar pinning and shape anisotropy both dependent on the width of the spacers
and the thickness of the stripes, as well as to the dynamical magnetic volume
charges formed due to inhomogeneous spin wave amplitude
Proposal for a standard micromagnetic problem: spin wave dispersion in a magnonic waveguide
In this paper, we propose a standard micromagnetic problem, of a nanostripe of permalloy. We study the magnetization dynamics and describe methods of extracting features from simulations. Spin wave dispersion curves, relating frequency and wave vector, are obtained for wave propagation in different directions relative to the axis of the waveguide and the external applied field. Simulation results using both finite element (Nmag) and finite difference (OOMMF) methods are compared against analytic results, for different ranges of the wave vector
Magnonic crystals — prospective structures for shaping spin waves in nanoscale
We have investigated theoretically band structure of spin waves in magnonic crystals with periodicity in one(1D),
two- (2D) and three-dimensions (3D). We have solved Landau–Lifshitz equation with the use of plane
wave method, finite element method in frequency domain and micromagnetic simulations in time domain to find
the dynamics of spin waves and spectrum of their eigenmodes. The spin wave spectra were calculated in linear
approximation. In this paper we show usefulness of these methods in calculations of various types of spin waves.
We demonstrate the surface character of the Damon–Eshbach spin wave in 1D magnonic crystals and change of
its surface localization with the band number and wavenumber in the first Brillouin zone. The surface property
of the spin wave excitation is further exploited by covering plate of the magnonic crystal with conductor. The
band structure in 2D magnonic crystals is complex due to additional spatial inhomogeneity introduced by the
demagnetizing field. This modifies spin wave dispersion, makes the band structure of magnonic crystals strongly
dependent on shape of the inclusions and type of the lattice. The inhomogeneity of the internal magnetic field
becomes unimportant for magnonic crystals with small lattice constant, where exchange interactions dominate.
For 3D magnonic crystals, characterized by small lattice constant, wide magnonic band gap is found. We show
that the spatial distribution of different materials in magnonic crystals can be explored for tailored effective
damping of spin wave