The growth- and frequency-dependent microwave studies on ~250 nm thick Y 3 Fe 5 O 12 yttrium iron garnet (YIG) films deposited on Gd 3 Ga 5 O 12 (111) (gadolinium gallium garnet) substrates by RF ...magnetron sputtering has been reported. After the deposition, the thin films were ex-situ annealed in air at 700 °C for different time intervals (2, 4, 6, and 10 h) and a pure YIG phase with preferred (111) orientation was formed. Effective saturation magnetization (<inline-formula> <tex-math notation="LaTeX">4\pi \text{M}_{\mathrm {eff}} </tex-math></inline-formula>) has been estimated from ferromagnetic resonance (FMR) data using Kittel's equations. A negative uniaxial magnetic anisotropy has been observed which decreased with the increase in annealing time. The FMR linewidth (<inline-formula> <tex-math notation="LaTeX">\Delta H </tex-math></inline-formula>) for the 10 h annealed film was found to be nearly half of the one annealed for 2 h. The 10 h annealed film showed a <inline-formula> <tex-math notation="LaTeX">\Delta H </tex-math></inline-formula> value which lies between 30 and 50 Oe over a wide frequency range (2-18 GHz). This improvement in the microwave properties as a result of annealing is attributed to the reduction of defects and relaxation of stress.
Vortex core polarity switching in NiFe disks has been evidenced using an all-electrical magnetoresistive rectification scheme. Simulation and experiments yield a consistent rectified signal loss when ...driving core gyration at high powers. With increasing power, the frequency range over which the loss occurs grows and the resonance downshifts in frequency, consistent with nonlinear core dynamics and periodic core polarity switching induced by the core reaching its critical velocity. Core-polarity-dependent rectification signals enable an independent verification of the switched core polarity. We also demonstrate the ability to impede core polarity switching by displacing the core towards the disk's edge where an increased core stiffness reduces the core velocity.
This article describes a novel approach which allows for the mutual determination of a ferromagnetic thin film's static and dynamic magnetic behaviours in the presence of an external thermodynamic ...stimulus. Using a combination of polarized neutron reflectometry (PNR) and ferromagnetic resonance (FMR) techniques, it is shown that information such as magnetic depth profiles and magnetization dynamics can be obtained for a ferromagnetic film in both transient and static states in the presence of a hydrogen gas atmosphere. Presented here are the proposed scheme, the instrumentation concept and the first experimental results obtained from implementing a custom‐made PNR with an in situ FMR sample chamber on the PLATYPUS time‐of‐flight reflectometer beamline at the Australian Centre for Neutron Scattering (ANSTO).
The design of a polarized neutron reflectometry sample environment capable of simultaneously measuring the ferromagnetic resonance response of a magnetic thin film is presented.
We investigate the ferromagnetic resonance response of palladium-cobalt bi-layer thin films to hydrogen charging at atmospheric pressure. Recently it has been found that hydrogen absorption by a ...palladium capping layer results in the narrowing and shifting of the ferromagnetic resonance peak of the underlying cobalt layer. This effect was explained as originating from a reduction in the spin pumping effect and a variation in the magnetic anisotropy of the cobalt layer. In this work we study the dependence of the shift of the resonance peak on the cobalt layer thickness. We observe a strong increase in the resonance peak field shift with a decrease in the cobalt layer thickness. In contrast, thicker Cobalt layers exhibit stronger changes in the absorption amplitude in the presence of hydrogen gas. Our results are important for optimization of Pd/Cobalt multi-layers as a novel platform for hydrogen gas sensing applications.
A review on recent Brillouin light scattering work on spin-wave modes in arrays of micrometer-size magnetic Ni80Fe20 stripes and rectangular elements is given. Several effects caused by the lateral ...confinement in the stripes are reviewed: 1. lateral quantization of dipole-dominated Damon–Eshbach spin-wave modes in a longitudinally magnetized stripe due to its finite width, 2. localization of exchange-dominated spin-wave modes near the edges and dipole-dominated spin-wave modes near the center of a transversely magnetized long magnetic stripe due to the inhomogeneity of its internal magnetic field, 3. combination of quantization and localization effects for the spin-wave modes in rectangular elements. The observed effects are analyzed using an analytical approach and numerical simulations.
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