Forbidden Band Gaps in the Spin-Wave Spectrum of a Two-Dimensional Bicomponent Magnonic Crystal (original) (raw)

Band Diagram of Spin Waves in a Two-Dimensional Magnonic Crystal

Physical Review Letters, 2011

The dispersion curves of collective spin-wave excitations in a magnonic crystal consisting of a square array of interacting saturated nanodisks have been measured by Brillouin light scattering along the four principal directions of the first Brillouin zone. The experimental data are successfully compared to calculations of the band diagram and of the Brillouin light scattering cross section, performed through the dynamical matrix method extended to include the dipolar interaction between the disks. We found that the fourfold symmetry of the geometrical lattice is reduced by the application of the external field and therefore equivalent directions of the first Brillouin zone are characterized by different dispersion relations of collective spin waves. The dispersion relations are explained through the introduction of a bidimensional effective wave vector that characterizes each mode in this magnonic metamaterial.

Partial frequency band gap in one-dimensional magnonic crystals

Applied Physics Letters, 2008

Collective spin wave modes propagating in an array of magnetic stripes coupled by dynamic dipole interaction are investigated by Brillouin light scattering. It is demonstrated that this structure supports propagation of discrete spin waves at any angle with respect to the stripes length. The data are interpreted using a theoretical model based on the Bloch wave approach. It is shown that, due to the one-dimensional artificial periodicity of the medium, the gaps in the spin wave spectrum are partial: the frequency passbands for propagation along the direction of periodicity overlap with the stop bands for propagation along the stripes.

Complete band gaps for magnetostatic forward volume waves in a two-dimensional magnonic crystal

Physical Review B, 2012

We report on the formation of a complete band gap for spin waves in a two-dimensional magnonic crystal consisting of a periodic hole lattice. We go beyond the partial band gaps observed so far in that we apply a magnetic field perpendicular to the permalloy thin film. We explore the relevant geometrical parameters using micromagnetic simulations. In nanopatterned devices we obtain complete band gaps of up to 1.4 GHz. The magnetostatic forward volume waves addressed here overcome in particular spin-wave localization effects. These effects have led to complicated and highly anisotropic miniband formation or Bragg reflection in in-plane fields for a long time. We demonstrate how direct band-gap tailoring via geometrical lattice symmetries becomes possible in nanostructured magnetic antidot lattices.

Collective spin waves in a bicomponent two-dimensional magnonic crystal

Applied Physics Letters, 2012

ABSTRACT Spin waves propagating in a bicomponent magnonic crystal consisting of a two-dimensional array of alternated NiFe and Co nanodots have been investigated. The frequency dispersion of collective modes, measured by Brillouin light scattering, is compared with the band diagram obtained by numerically solving the eigenvalue problem derived from the linearized Landau-Lifshitz magnetic torque equation. It is shown that the modes which are active in Brillouin experiment are characterized by the simplest modal profiles within the NiFe dots. For such excitations, the Co dots act as mediators of dipole coupling between the NiFe dots. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704659\]

Band structures of exchange spin waves in one-dimensional bi-component magnonic crystals

2012

Abstract We present the micromagnetic study of magnonic band structures for exchange spin waves propagating in one-dimensional magnonic crystals. The crystals are of laterally patterned periodic arrays of alternating cobalt and nickel stripes. Large magnonic bandgaps with widths of tens of GHz are observed. It is found that the higher-order transmission bands and bandgaps have wider widths than those of the lower-order bands and bandgaps.

Anisotropic spin waves in two-dimensional triangular shaped bi-component magnonic crystal

Journal of Magnetism and Magnetic Materials, 2019

Bi-component magnonic crystals with a strong dipole-exchange interaction across the interface of the constituent magnetic elements have shown promising potentials in magnonics and magnon-spintronics. Here, we have reported an all-optical investigation of spin wave dynamics in an array of periodically arranged bi-component magnonic crystal in the form of triangular shaped Ni 80 Fe 20 nanoelements embedded in Co 50 Fe 50 matrix using time-resolved magneto-optical Kerr effect magnetometry. The spin wave spectra obtained from the sample reveal a broad band of spin wave modes where they possess a strong and systematic bias magnetic field tunability which is crucial for active control over such system in device applications. Further, the spin wave modes show a six-fold and a four-fold rotational anisotropy with the bias field orientation due to combined effects of element shape and lattice symmetry. Micromagnetic simulations reproduce the experimental results qualitatively where the simulated mode profiles unravel the spatial distribution of spin wave frequencies inside both constituent elements while the internal magnetic fields play a crucial role for the observed tunability of spin wave dynamics. Development of such magnetically coupled embedded magnetic nanostructures can pave a new pathway in designing the future magnonic devices and faster microwave communication systems.

Brillouin light scattering studies of planar metallic magnonic crystals

Journal of Physics D: Applied Physics, 2010

The application of Brillouin light scattering to the study of the spin-wave spectrum of one-and two-dimensional planar magnonic crystals consisting of arrays of interacting stripes, dots and antidots is reviewed. It is shown that the discrete set of allowed frequencies of an isolated nanoelement becomes a finite-width frequency band for an array of identical interacting elements. It is possible to tune the permitted and forbidden frequency bands, modifying the geometrical or the material magnetic parameters, as well as the external magnetic field. From a technological point of view, the accurate fabrication of planar magnonic crystals and a proper understanding of their magnetic excitation spectrum in the GHz range is oriented to the design of filters and waveguides for microwave communication systems.

Magnonic Crystal with Two-Dimensional Periodicity as a Waveguide for Spin Waves

2010

We describe a simple method of including dissipation in the spin wave band structure of a periodic ferromagnetic composite, by solving the Landau-Lifshitz equation for the magnetization with the Gilbert damping term. We use this approach to calculate the band structure of square and triangular arrays of Ni nanocylinders embedded in an Fe host. The results show that there are certain bands and special directions in the Brillouin zone where the spin wave lifetime is increased by more than an order of magnitude above its average value. Thus, it may be possible to generate spin waves in such composites decay especially slowly, and propagate especially large distances, for certain frequencies and directions in bfk{\bf k}bfk-space.