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.

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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.

We show that sputtered, pure epitaxial iron films can have high-frequency loss as low as, or lower than, any known metallic ferromagnetic heterostructure. Minimum 34GHz ferromagnetic resonance linewidths of 41±2Oe are demonstrated, some ∼5%–10% lower than the previous minimum reported for molecular beam epitaxially deposited Fe. Intrinsic and extrinsic damping have been separated over 0–40GHz, giving a lower bound for intrinsic LL(G) relaxation rates of λ or G=85±5MHz (α=0.0027±0.0001) and for extrinsic η∼30–50MHz. Swept-frequency measurements indicate the potential for integrated frequency domain devices with Q>100 at 30–40Ghz.

We report the structural and magnetic properties of Ni films grown on GaAs(001) using electrodeposition, covering the thickness range 0–80 nm. The structure is characterized by mixed (001) and (011) epitaxial orientation of fcc Ni with a preference for the Ni(001) orientation. The magnetic anisotropy is originated by a combination of a crystalline contribution with fourfold symmetry and a uniaxial anisotropy probably caused by the asymmetry in the substrate surface structure. The saturation magnetic moment varies linearly with thickness, indicating limited intermixing between Ni film and GaAs substrate. This is ascribed to the low-energy deposition process characteristic of electrodeposition.

We demonstrate selective electrodeposition of magnetic layers on doped semiconductors resulting in a self-aligned pattern which replicates the doping pattern in the semiconductor surface. A Schottky barrier forms at the interface between a semiconductor substrate and the electrolyte, which upon application of a cathodic potential is biased in the forward (reverse) direction for n- or p-type semiconductors, respectively. Electron transfer from an n-type semiconductor is thus possible, while breakdown of the Schottky barrier would be necessary for deposition on a p-type substrate. The process will thus be spatially selective on a lateral modulation of the substrate doping. As an example we demonstrate the deposition of Co on GaAs.

Brillouin light scattering from thermal spin waves has been exploited to investigate the thickness dependence of magnetic anisotropy of Ni films, with thickness in the range 7–35nm, grown by electrodeposition onto either (011)- or (001)-GaAs substrates. In the former case, Ni films exhibit a well-defined in-plane uniaxial anisotropy induced by the symmetry of the substrate. In the case of the (001)-GaAs substrate, instead, the magnetic anisotropy results from a combination of both a fourfold and a twofold contribution. The physical mechanisms responsible for the observed anisotropy, as well as its dependence on film thickness, are discussed in detail.