Engineered Magnetization Dynamics of Magnonic Nanograting Filters
TL;DR: In this paper, the effect of nanowire damping, excitation frequency and geometry on the spin wave modes, spatial and temporal transmission profiles for a finite patterned nanograting under external direct current (DC) and radio frequency (RF) magnetic fields was investigated.
Abstract: Magnonic crystals and gratings could enable tunable spin-wave filters, logic, and frequency multiplier devices. Using micromagnetic models, we investigate the effect of nanowire damping, excitation frequency and geometry on the spin wave modes, spatial and temporal transmission profiles for a finite patterned nanograting under external direct current (DC) and radio frequency (RF) magnetic fields. Studying the effect of Gilbert damping constant on the temporal and spectral responses shows that low-damping leads to longer mode propagation lengths due to low-loss and high-frequency excitations are also transmitted with high intensity. When the nanowire is excited with stronger external RF fields, higher frequency spin wave modes are transmitted with higher intensities. Changing the nanowire grating width, pitch and its number of periods helps shift the transmitted frequencies over super high-frequency (SHF) range, spans S, C, X, Ku, and K bands (3–30 GHz). Our design could enable spin-wave frequency multipliers, selective filtering, excitation, and suppression in magnetic nanowires.
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Journal Article•
TL;DR: In this article, a one-dimensional magnonic crystal for forward volume spin waves (FV SWs) is demonstrated using eight pairs of Cu stripes fabricated on a 1-mm wide × 14-mm long × 10.2-μm thick yttrium iron garnet (YIG) waveguide and a SW absorber of 30-nm-thick Au film.
Abstract: A one-dimensional magnonic crystal for forward volume spin waves (FV SWs) is demonstrated using eight pairs of Cu stripes fabricated on a 1-mm wide × 14-mm long × 10.2-μm thick yttrium iron garnet (YIG) waveguide and a SW absorber of 30-nm-thick Au film. The development of this crystal is challenging due to strong spectral oscillations caused by edge reflections and process difficulties associated with YIG magnonic crystals. A magnonic band gap with a depth of −4.6 dB is observed at a frequency of 1.80 GHz for a FV SW excited by a 50-μm-wide microstrip line, which is in good agreement with simulation results using three-dimensional modeling in the radio frequency region. The obtained performance is illustrated by plotting the depth of the respective band gaps vs the pair number of the stripes. This value is compared with that obtained in previous studies.
8 citations
Posted Content•
TL;DR: In this article, the reprogrammable spin wave band structure in Permalloy(10nm)/Cu(5nm)/PermAlloy(30nm) nanowire arrays of width w=280 nm and inter-wire separation in the range from 80 to 280 nm was studied both experimentally and theoretically.
Abstract: We have studied both experimentally and theoretically the reprogrammable spin wave band structure in Permalloy(10nm)/Cu(5nm)/Permalloy(30nm) nanowire arrays of width w=280 nm and inter-wire separation in the range from 80 to 280 nm. We found that, depending on the inter-wire separation, the anti-parallel configuration, where the magnetizations of the two Permalloy layers point in opposite directions, is stabilized over specific magnetic field ranges thus enabling us to directly compare the band structure with that of the parallel alignment. We show that collective spin waves of the Bloch type propagate through the arrays with different magnonic bandwidths as a consequence of the interplay between the intra- and inter-nanowire dynamic dipolar interactions. A detailed understanding, e.g. whether they have a stationary or propagating character, is achieved by considering the phase relation (in-phase or out-of-phase) between the dynamic magnetizations in the two ferromagnetic layers and their average value. This work opens the path to magnetic field-controlled reconfigurable layered magnonic crystals that can be used for future nanoscale magnon spintronic devices.
1 citations
References
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TL;DR: In this article, the experimental observation of band gaps in a synthetic nanostructured magnonic crystal composed of two different magnetic materials was reported, in the form of a one-dimensional periodic array comprising alternating Permalloy and cobalt nanostripes.
Abstract: We report the experimental observation of band gaps in a synthetic nanostructured magnonic crystal composed of two different magnetic materials. The sample, in the form of a one-dimensional periodic array comprising alternating Permalloy and cobalt nanostripes, has been fabricated using advanced lithographic techniques. Dispersion relations of spin waves in the magnonic crystal have been mapped by Brillouin spectroscopy. The center frequency and width of the band gaps observed are tunable by an applied magnetic field. Dispersion relations calculated based on the finite element method accord with the measured data.
243 citations
TL;DR: An exciting recent development is that the spin torque effect in nanoferromagnets is described by a generalization of the LLG equation that forms a basic dynamical equation in the field of spintronics.
Abstract: The Landau–Lifshitz–Gilbert (LLG) equation is a fascinating nonlinear evolution equation both from mathematical and physical points of view. It is related to the dynamics of several important physical systems such as ferromagnets, vortex filaments, moving space curves, etc. and has intimate connections with many of the well-known integrable soliton equations, including nonlinear Schrodinger and sine-Gordon equations. It can admit very many dynamical structures including spin waves, elliptic function waves, solitons, dromions, vortices, spatio-temporal patterns, chaos, etc. depending on the physical and spin dimensions and the nature of interactions. An exciting recent development is that the spin torque effect in nanoferromagnets is described by a generalization of the LLG equation that forms a basic dynamical equation in the field of spintronics. This article will briefly review these developments as a tribute to Robin Bullough who was a great admirer of the LLG equation.
230 citations
TL;DR: In this article, a planar structure of magnonic-crystal waveguides, made of a single magnetic material, was reported, in which the allowed and forbidden bands of propagating dipole-exchange spin waves can be manipulated by the periodic modulation of different widths in thin-film nanostrips.
Abstract: We report, for the first time, on a novel planar structure of magnonic-crystal waveguides, made of a single magnetic material, in which the allowed and forbidden bands of propagating dipole-exchange spin waves can be manipulated by the periodic modulation of different widths in thin-film nanostrips. The origin of the presence of several magnonic wide band gaps and the crucial parameters for controlling those band gaps of the order of $\ensuremath{\sim}10\text{ }\text{ }\mathrm{GHz}$ are found by micromagnetic numerical and analytical calculations. This work can offer a route to the potential application to broadband spin wave filters in the gigahertz frequency range.
212 citations
TL;DR: In this paper, a grating of shallow grooves etched into the surface of an yttrium iron garnet film was experimentally studied, and the rejection frequency bands were clearly observed.
Abstract: 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.
176 citations
TL;DR: A reconfigurable waveguide design is proposed that can transmit and locally manipulate spin waves without the need for any external bias field once initialized, and a binary gating of the spin-wave signal is experimentally shown by controlled switching of the magnetization, locally, in the waveguide.
Abstract: Spin-wave-based devices promise to usher in an era of low-power computing where information is carried by the precession of the electrons' spin instead of dissipative translation of their charge. This potential is, however, undermined by the need for a bias magnetic field, which must remain powered on to maintain an anisotropic device characteristic. Here, we propose a reconfigurable waveguide design that can transmit and locally manipulate spin waves without the need for any external bias field once initialized. We experimentally demonstrate the transmission of spin waves in straight as well as curved waveguides without a bias field, which has been elusive so far. Furthermore, we experimentally show a binary gating of the spin-wave signal by controlled switching of the magnetization, locally, in the waveguide. The results have potential implications in high-density integration and energy-efficient operation of nanomagnetic devices at room temperature.
155 citations