The phenomenon of coherent wave trapping and restoration is demonstrated experimentally in a magnonic crystal. Unlike the conventional scheme used in photonics, the trapping occurs not due to the ...deceleration of the incident wave when it enters the periodic structure but due to excitation of the quasinormal modes of the artificial crystal. This excitation occurs at the group velocity minima of the decelerated wave in narrow frequency regions near the edges of the band gaps of the crystal. The restoration of the traveling wave is implemented by means of phase-sensitive parametric amplification of the stored mode.
•We have studied the spin wave properties in longitudinally and transversely magnetized single- and bi-layer nanowire arrays.•In the former case, filtering properties associated with the existence of ...allowed and forbidden frequency ranges were observed.•In the latter case, the SW dispersion is monotonic with number of modes and SW group velocity which markedly depend on the NW composition.•This study demonstrates that a proper choice of magnetic materials and layer structure represents and efficient way for tuning the dynamical properties of such periodic arrays of magnetic nano-elements.
We have investigated the spin wave filtering and guiding properties of periodic array of single (Permalloy and Fe) and bi-layer (Py/Fe) nanowires (NWs) by means of Brillouin light scattering measurements and micromagnetic simulations. For all the nanowire arrays, the thickness of the layers is 10nm while all NWs have the same width of 340nm and edge-to-edge separation of 100nm. Spin wave dispersion has been measured in the Damon-Eshbach configuration for wave vector either parallel or perpendicular to the nanowire length. This study reveals the filtering property of the spin waves when the wave vector is perpendicular to the NW length, with frequency ranges where the spin wave propagation is permitted separated by frequency band gaps, and the guiding property of NW when the wave vector is oriented parallel to the NW, with spin wave modes propagating in parallel channels in the central and edge regions of the NW. The measured dispersions were well reproduced by micromagnetic simulations, which also deliver the spatial profiles for the modes at zero wave vector. To reproduce the dispersion of the modes localized close to the NW edges, uniaxial anisotropy has been introduced. In the case of Permalloy/iron NWs, the obtained results have been compared with those for a 20nm thick effective NW having average magnetic properties of the two materials.
We have studied both experimentally and theoretically the reprogrammable spin wave band structure in Permalloy(10 nm)/Cu(5 nm)/Permalloy(30 nm) 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.
In this work we study the ferromagnetic resonance (FMR) response of CoxPd1-x alloy samples with varying compositions (x = 0.65, 0.39, 0.24 and 0.14). We find significant differences in the FMR ...response of the samples to the presence of hydrogen gas in the samples’ environment. Without any special processing, the films with x = 0.39 and 0.24 demonstrated behaviour which is promising for application in hydrogen gas sensing. Using FMR in the alloy thin films, we were able to measure hydrogen gas concentration in a very broad range - from 0.05% to 100%.
•Ferromagnetic resonance (FMR) in PdCo alloy films was investigated in the presence of hydrogen gas.•The FMR was shown to be sensitive to a broad range of concentrations of the gas.•The sensitivity is non-vanishing from 0.05% to 100% of hydrogen in the environment.
•The magnetization obtained from FMR is found to be 2600 G.•Observation of large negative anisotropy field (HU).•The stress induced in the film is the primary cause for such a large negative HU.•The ...presence of this stress in YIG film was confirmed using multiple GIXRD.•Systematic FMR and dc magnetic studies in the temperature range 4.2 ≤ T ≤ 300 K.
Magnetic properties and FMR of pulsed laser deposited Y3Fe5O12 (YIG) thin film on Gd3Ga5O12 (1 1 1) substrate have been investigated in the temperature range 4.2 ≤ T ≤ 300 K. The effective saturation magnetization (4πMeff), obtained from Ferromagnetic Resonance at room temperature, is found to be 2600 G, which is higher than SQUID measured 4πMS value of 1770 G. This implies that the value of 4πMeff can only be accounted by considering a negative anisotropy field (HU) of around 830 Oe at room temperature. Such an anisotropy is attributed to a compressive stress (−1.70 × 1010 dyne/cm2) induced in the film closer to the film-air interface. The presence of this stress in YIG film was confirmed using multiple {hkl} stress measurements with grazing incidence X-ray diffraction performed at different depth of penetration on the YIG film.
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