Abstract
The magnetization dynamics of an yttrium iron garnet (YIG)/Au/YIG magnon valve was investigated using broadband ferromagnetic resonance. The material characterizations of YIG/Au/YIG were performed using cross-sectional scanning transmission electron microscopy, x-ray diffraction spectroscopy, x-ray photoemission spectroscopy, Raman spectroscopy, and UV–visible spectroscopy. Asymmetric Fano resonance in the YIG/Au (60 nm)/YIG magnon valve structure was observed experimentally, and the two coupled oscillators model was used to describe the source of the Fano resonance qualitatively. We also provide a quantitative description of the Fano resonance and extract the Fano factor, which is an important feature that can be used to define the interaction sign. This represents the first attempt to apply the Fano resonance to magnetization dynamics. The spin wave resonance modes excited by the Au nanoparticles (NPs) surface plasmons were also observed in a YIG/Au NPs/YIG structure. Our findings confirm the occurrence of magnetic Fano resonance in the YIG/Au/YIG magnon valve and pave the way toward the development of quantum information devices based on magnon valves.
Highlights
The interlayer exchange interaction properties of the yttrium iron garnet (YIG)/Au (t nm)/YIG structures were characterized by ferromagnetic resonance (FMR) spectroscopy
In FMR testing, the sample is placed upside down on a waveguide, and the magnetic field HDC is homogeneous along the waveguide signal line in the area of the sample; the film precessions are driven by an applied radio-frequency field
This work presents a systematic investigation of the magnetization dynamics of a YIG/Au/YIG magnon valve
Summary
Following the observation of the giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) effects, magnetic multilayers composed of ferromagnetic (FM) and nonmagnetic films have drawn considerable interest from researchers because of their potential applications in spintronic devices, including magnetic random-access memory devices, spin logic devices, and magnetic read heads. Grünberg et al discovered the interlayer exchange coupling that occurs between ferromagnetic layers through a nonmagnetic spacer layer in Fe/Cr/Fe multilayer structures using light scattering from spin waves. The oscillation of interlayer exchange coupling in NiCo/Ru/NiCo multilayers was demonstrated by Parkin and Mauri. Heinrich et al discovered a long-range dynamic interaction between ferromagnetic films separated by normal metal spacers and explained this interaction using adiabatic spin-pump theory. Heinrich et al studied the spin injection at the yttrium iron garnet (YIG)/Au interface using ferromagnetic resonance (FMR). The relationship between the static and dynamic coupling was obtained by comparing the Gilbert damping that occurred in bare YIG films with that observed in a YIG/Au/Fe/Au structure, where the results provided direct evidence for the spinpump theory. Grünberg et al discovered the interlayer exchange coupling that occurs between ferromagnetic layers through a nonmagnetic spacer layer in Fe/Cr/Fe multilayer structures using light scattering from spin waves.. We report the magnetization dynamics properties of the YIG/Au/YIG magnon valve. Fano resonance is a quantum effect with a non-Lorentzian spectrum derived from constructive and destructive interference in the near field This resonance usually has a high Q factor and an extremely localized near-field. The material microstructure characterizations and magnetization dynamics of YIG/Au/YIG magnon valve heterostructures are presented. The study of the high Q factor of Fano line shapes can define the interaction sign This method is useful when the resonance frequencies of the two interacting layers lie close to each other.. This method is useful when the resonance frequencies of the two interacting layers lie close to each other. Fano resonance arises from the magnon valve, providing superior tunability under various external frequencies
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