Nanostripe of subwavelength width as a switchable semitransparent mirror for spin waves in a magnonic crystal

Huber, Rupert; Schwarze, Thomas; Grundler, D.

doi:10.1103/physrevb.88.100405

Cited by 19 publications

(17 citation statements)

References 22 publications

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“…by m A M SA + m B M SA . Thus, to list a few topics of relevance, we expect the problems of spin wave scattering from interfaces [83][84][85][86] (including the recently proposed magnonic Goos-Hänchen effect 87 ), spin wave dispersion in magnonic crystals 24,32,44,46,47,88 and quasi-crystals, 38,89,90 spectra and localization of defect and surface modes, 91,92,93 and associated applications in magnonic devices 14,40,41,94 to be revisited with the generalized Barnaś-Mills boundary conditions derived here.…”

Section: Discussionmentioning

confidence: 99%

Magnetization boundary conditions at a ferromagnetic interface of finite thickness

Kruglyak

Gorobets

et al. 2014

J. Phys.: Condens. Matter

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We develop a systematic approach by which to derive boundary conditions at an interface between two ferromagnetic materials in the continuous medium approximation. The approach treats the interface as a two-sublattice material, although the final equations connect magnetizations outside of the interface and therefore do not explicitly depend on its structure. Instead, the boundary conditions are defined in terms of some average properties of the interface, which may also have a finite thickness. In addition to the interface anisotropy and symmetric exchange coupling, this approach allows us to take into account coupling resulting from inversion symmetry breaking in the vicinity of the interface, such as the Dzyaloshinskii-Moriya antisymmetric exchange interaction. In the case of negligible interface anisotropy and Dzyaloshinskii-Moriya exchange parameters, the derived boundary conditions represent a generalization of those proposed earlier by Barnaś and Mills and are therefore named "generalized Barnaś-Mills boundary conditions". We demonstrate how one could use the boundary conditions to extract parameters of the interface via fitting of appropriate experimental data. The developed theory could be applied to modeling of both linear and non-linear spin waves, including exchange, dipole-exchange, magnetostatic, and retarded modes, as well as to calculations of nonuniform equilibrium micromagnetic configurations near the interface, with a direct impact on the research in magnonics and micromagnetism. * Corresponding author: V.V.Kruglyak@exeter.ac.uk 2

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Section: Discussionmentioning

confidence: 99%

Magnetization boundary conditions at a ferromagnetic interface of finite thickness

Kruglyak

Gorobets

et al. 2014

J. Phys.: Condens. Matter

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“…As applied to spin waves, this concept is based on the following basic ideas. First, the propagation of spin waves is controlled using subwavelength, often continuously varying, magnetic nonuniformities [8,9]. This should minimize scaling of the device size with the magnonic wavelength, in contrast to, e.g., magnonic crystal based approaches [3], and thereby ease the associated patterning resolution requirements.…”

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confidence: 99%

Towards graded-index magnonics: Steering spin waves in magnonic networks

et al. 2015

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Magnonics explores precessional excitations of ordered spins in magnetic materials-so-called spin wavesand their use as information and signal carriers within networks of magnonic waveguides. Here, we demonstrate that the nonuniformity of the internal magnetic field and magnetization inherent to magnetic structures creates a medium of graded refractive index for propagating magnetostatic waves and can be used to steer their propagation. The character of the nonuniformity can be tuned and potentially programmed using the applied magnetic field, which opens exciting prospects for the field of graded-index magnonics. Over the past decade, magnonics (the study of spin waves-precessional excitations of ordered spins in magnetic materials [1]) has emerged as one of the most rapidly growing research fields in magnetism [2,3]. Moreover, recent advances in the understanding of fundamental properties of spin waves in magnetic micro-and nanostructures have highlighted magnonics as a potential rival of or complement to semiconductor technology in the field of data communication and processing [4]. The push for miniaturization renders ferromagnetic transition metals and their alloys to be materials of choice for the fabrication of spin-wave devices [5,6]. However, loss reduction, the shortening of the wavelength of studied spin waves, and the associated miniaturization of the implemented magnonic concepts and devices remain major challenges in both experimental research and technological development in magnonics [2,3].In this Rapid Communication, we explore an approach to meet these challenges that is based on the concept of gradedindex (or gradient-index) optics [7]. As applied to spin waves, this concept is based on the following basic ideas. First, the propagation of spin waves is controlled using subwavelength, often continuously varying, magnetic nonuniformities [8,9]. This should minimize scaling of the device size with the magnonic wavelength, in contrast to, e.g., magnonic crystal based approaches [3], and thereby ease the associated patterning resolution requirements. Indeed, nonuniform effective magnetic field and magnetization configurations have been shown to confine [10,11] and channel [12][13][14][15] spin waves, to continuously modify their character [16][17][18], and to enable their coupling to essentially uniform free space microwaves [19,20]. Here, we go further by exploiting in addition the anisotropic dispersion inherent to spin waves dominated by the dynamic magneto-dipole field-so-called magnetostatic spin waves [1]. The symmetry axis of the anisotropic magnetostatic dispersion coincides with the direction of the magnetization [21][22][23]. This anisotropic dispersion leads to the formation of nondiffracting caustic spin-wave beams * Corresponding author: v.v.kruglyak@exeter.ac.uk [24][25][26][27][28][29][30] and to anomalous spin-wave reflection, refraction, and diffraction [31][32][33][34][35]. Here, we explore these ideas in networks of magnonic waveguides [6,8,[12][13][14][15][16][17][18][19][20]24,...

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“…(70) The possibility for control of the magnetization alignment in the arrays of stripes (ferromagnetic or antiferromagnetic) has allowed demonstration of the re-programmable magnonic band structure in MCs. (71)(72)(73)(74)(75) The periodicity in magnonic systems can also be introduced in other ways. For instance, the periodic modulation of the external magnetic field applied to homogeneous film is sufficient to create magnonic bands and band gaps.…”

Section: D Magnonic Crystalsmentioning

confidence: 99%

“…It means that the same element can have various spin wave dynamics depending on the static magnetization configuration, similar to changes of the resistivity in GMR and TMR structures for electric current. The operational functionality of magnonic device or its sub unit can be reprogrammed effectively (70)(71)(72) and used, for instance, to prototype magnonic transistors. (23) All these properties make magnonics and especially MCs of thin-film geometry, which is a main building block of magnonics, although interesting also for a number of other fields of nanoscience and nanotechnology.…”

Section: Applicationsmentioning

confidence: 99%

Magnonic Crystals

Gruszecki

Krawczyk

2016

Wiley Encyclopedia of Electrical and Electronics Engineering

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Magnonic crystals can be regarded as the magnetic counterpart of photonic crystals, with spin waves acting as information carriers. Thus, magnonic crystals are magnetic materials with periodic distribution of the constituents or periodic modulation of some magnetic parameters (e.g., saturation magnetization or magnetocrystalline anisotropy), or other parameters relevant to the propagation of spin waves (e.g., external magnetic field, film thickness, stress, or a surrounding of the homogeneous ferromagnetic film). The spin waves propagating in magnonic crystal have a form of Bloch waves, and the dispersion relation includes frequency bands allowing spin wave propagation and frequency band gaps, forbidden for spin wave propagation. By adjusting relevant parameters of the magnonic crystal or external fields, the spectrum of spin waves can be tuned and the flow of spin waves can be tailored in the way unavailable with homogeneous media. The new physical effects occurring in magnetic nanostructures with periodic pattern and prospective applications of magnonic crystals, especially in integrated microwave devices and for processing information at microwave frequencies, drive the new fields of magnonics and magnon spintronics.

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Nanostripe of subwavelength width as a switchable semitransparent mirror for spin waves in a magnonic crystal

Cited by 19 publications

References 22 publications

Magnetization boundary conditions at a ferromagnetic interface of finite thickness

Magnetization boundary conditions at a ferromagnetic interface of finite thickness

Towards graded-index magnonics: Steering spin waves in magnonic networks

Magnonic Crystals

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