The longest relaxation time and sharpest frequency content in ferromagnetic precession is determined by the intrinsic (Gilbert) relaxation rate G. For many years, pure iron (Fe) has had the lowest known value of G = 57 MHz for all pure ferromagnetic metals or binary alloys. We show that an epitaxial iron alloy with vanadium (V) possesses values of G which are significantly reduced to 35 +/- 5 MHz at 27% V. The result can be understood as the role of spin-orbit coupling in generating relaxation, reduced through the atomic number Z.
We report on the chemical, electrical, and magnetic properties of Ni/GaAs(001) interfaces prepared using electrodeposition. Electrodeposition is an equilibrium process which thus releases much less energy per absorbed atom than other deposition techniques. This allows preparation of chemically sharp interfaces which otherwise show a high degree of reactivity and interdiffusion. This is demonstrated by the example of Ni grown on GaAs(001). Photoelectron spectroscopy shows the absence of surface segregation of substrate material or diffusion into the Ni layer. This is confirmed by the electrical and magnetic properties of the films.
We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect.
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