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

Tacchi, S.; Duerr, G.; Kłos, Jarosław W.; Madami, M.; Neusser, S.; Gubbiotti, G.; Carlotti, G.; Krawczyk, Maciej; Grundler, D.

doi:10.1103/physrevlett.109.137202

Cited by 116 publications

(90 citation statements)

References 22 publications

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“…Much theoretical and experimental research has been done on the spin dynamics of defect-free MCs. 3,4,[6][7][8][9][10][11][12] However, investigations into defect-induced phenomena in MCs have not been as extensively undertaken as those for photonic a phykmh@nus.edu.sg. crystals.…”

Section: Introductionmentioning

confidence: 99%

Spin-wave dispersion of nanostructured magnonic crystals with periodic defects

Zhang

Lim

et al. 2016

AIP Advances

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The spin-wave dispersions in nanostructured magnonic crystals with periodic defects have been mapped by Brillouin light scattering. The otherwise perfect crystals are one-dimensional arrays of alternating 460nm-wide Ni80Fe20 stripes and 40nm-wide air gaps, where one in ten Ni80Fe20 stripes is a defect of width other than 460 nm. Experimentally, the defects are manifested as additional Brillouin peaks, lying within the first and second bandgaps of the perfect crystal, whose frequencies decrease with increasing defect stripe width. Finite-element calculations, based on a supercell comprising one defect and nine perfect Py stripes, show that the defect modes are localized about the defects, with the localization exhibiting an approximate U-shaped dependence on defect size. Calculations also reveal extra magnon branches and the opening of mini-bandgaps, within the allowed bands of the perfect crystal, arising from Bragg reflections at the boundaries of the shorter supercell Brillouin zone. Simulated magnetization profiles of the band-edge modes of the major and mini-bandgaps reveal their different symmetries and localization properties. The findings could find application in microwave magnonic devices like single-frequency passband spin-wave filters.

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Section: Introductionmentioning

confidence: 99%

Spin-wave dispersion of nanostructured magnonic crystals with periodic defects

Zhang

Lim

et al. 2016

AIP Advances

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“…Bi-component magnonic crystals (BMCs) consisting of two different periodically arranged magnetic materials have attracted great interest in recent years because of the possibility of tuning the spin wave (SW) band structure, such as the frequency position and the width of the allowed band and forbidden bandgap, 1,2,3,4,5,6,7 thanks to the additional degrees of freedom offered by the contrasting properties of the ferromagnetic (FM) materials.…”

Section: Introductionmentioning

confidence: 99%

Collective spin excitations in bicomponent magnonic crystals consisting of bilayer permalloy/Fe nanowires

et al. 2016

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In the developing field of magnonics, it is very important to achieve tailoring of spin wave propagation by both a proper combination of materials with different magnetic properties and their nanostructuring on the submicrometric scale. With this in mind, we have exploited deep ultra-violet lithography, in combination with tilted shadow deposition technique, to fabricate arrays of closely spaced bi-layer nanowires (NWs), with separation d=100 nm and periodicity a=440 nm, having bottom and top layers made of Permalloy and Iron, respectively. The NWs have either "rectangular" cross section (bottom and upper layers of equal width) or "L-shaped" cross section (upper layer of half width). The frequency dispersion of collective spin wave excitations in the above bi-layered NWs arrays has been measured by the Brillouin light scattering technique while sweeping the wave vector perpendicularly to the wire length over three Brillouin zones of the reciprocal space. For the rectangular NWs, the lowest-frequency fundamental mode, characterized by a quasi-uniform profile of the amplitude of the dynamic magnetization across the NW width, exhibits a sizeable and periodic frequency dispersion. A similar dispersive mode is also present in L-shaped NWs, but the mode amplitude is concentrated in the thin side of the NWs. The width and the center frequency of the magnonic band associated with the above fundamental modes has been analysed, showing that both can be tuned by varying the external applied field. Moreover, for the L-shaped NWs it is shown that there is also a second dispersive mode, at higher frequency, characterized by an amplitude concentrated in the thick side of the NW. These experimental results have been quantitatively reproduced by an original numerical model that includes two-dimensional Green's 2 function of the dipole field of the dynamic magnetization and interlayer exchange coupling between the layers.

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“…The term magnonics has been coined to describe this field of study [5,6]. One pathway to control magnon dispersions is to construct magnonic crystals [7,8] that are metamaterials with a spatial modulation of the magnetic properties on length scales comparable to relevant magnonic wavelengths [9][10][11]. Patterned thin magnetic films [12,13] or topographically modulated thin films have been used to manipulate the magnon spectra [14].…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable wave band structure of an artificial square ice

et al. 2016

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Artificial square ices are structures composed of magnetic nanoelements arranged on the sites of a twodimensional square lattice, such that there are four interacting magnetic elements at each vertex, leading to geometrical frustration. Using a semianalytical approach, we show that square ices exhibit a rich spin-wave band structure that is tunable both by external magnetic fields and the magnetization configuration of individual elements. Internal degrees of freedom can give rise to equilibrium states with bent magnetization at the element edges leading to characteristic excitations; in the presence of magnetostatic interactions these form separate bands analogous to impurity bands in semiconductors. Full-scale micromagnetic simulations corroborate our semianalytical approach. Our results show that artificial square ices can be viewed as reconfigurable and tunable magnonic crystals that can be used as metamaterials for spin-wave-based applications at the nanoscale.

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

Cited by 116 publications

References 22 publications

Spin-wave dispersion of nanostructured magnonic crystals with periodic defects

Spin-wave dispersion of nanostructured magnonic crystals with periodic defects

Collective spin excitations in bicomponent magnonic crystals consisting of bilayer permalloy/Fe nanowires

Reconfigurable wave band structure of an artificial square ice

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