The electronic as well as magnetic properties of GaxFe1−x films were studied by soft x-ray measurements. Using x-ray magnetic circular dichroism the Fe majority spin band was found to be completely filled for x ≈ 0.3. With further enhanced Ga content, the Fe moment as well as the angular dependence of the x-ray magnetic linear dichroism decrease strongly, which we attribute to the formation of D03 precipitates. Moreover, the magnetocrystalline anisotropy drops significantly.

Modern, high frequency, microwave devices for communications technologies can be made with thin ferromagnetic films with narrow microwave resonance linewidths. Recently, there has been interest in magnetostrictive materials where the material constants can change substantially with stresses and applied magnetic fields. We report the development of single crystal thin (20 nm thick) magnetostrictive films of Fe1−xGax (x = 0.20 FeGa(A), 0.23 FeGa(B), 0.28 FeGa(C) on GaAs(001) substrates and on their use in prototype microwave devices. These Galfenol films have a narrower linewidth than any previously reported similar thin films. We fabricate and characterize novel microstrip-based monolithic microwave devices using Galfenol thin films as an active element. We find a number of important features: (1) There is a large absorption (up to 30 dB/cm) at the resonance frequency. (2) The linewidth of the device is narrow ∼1.5 GHz. (3) The saturation magnetization of the samples decreases with the increase in Ga contents. (4) The cubic anisotropy is close to zero (∼0.06 kOe for FeGa(A)) and becomes negative for higher concentration of Ga content in the samples, and (5) the damping increases with increase in Ga concentration.

Molecular beam epitaxy was used to deposit single crystal thin film Fe 1−x Ga x samples on ZnSe buffer layers grown on ͑001͒ and ͑110͒ single crystal GaAs substrates. The crystal quality of the GaAs surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetic properties of the samples were characterized by vibrating sample magnetometry and ferromagnetic resonance ͑FMR͒. The FMR linewidth increases dramatically with Ga concentration while the cubic anisotropy term K 1 switches sign.

The magnetic properties of single crystal Fe1−xGax thin films deposited on ZnSe/GaAs(001) and MgO(001) substrates by molecular beam epitaxy were investigated by vibrating sample magnetometry and angle dependent ferromagnetic resonance. Depositions on the ZnSe buffer layer feature a strong uniaxial anisotropy that scales with the thin film magnetostriction of the samples, while depositions on MgO(001) substrates result in a purely cubic anisotropy whose cubic anisotropy constant, K1, switches sign at a lower Ga concentration than is seen in bulk.

Molecular beam epitaxy was used to deposit body centered cubic single crystal Fe^Ga, thin films on MgO(OOl) and ZnSe/GaAs(001) substrates well beyond the bulk stability concentration of about 28%. The crystal quality of the substrate surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetization of the samples as a function of Ga is found to decrease more rapidly than a simple dilution effect, and element-specific x-ray magnetic circular dichroism ascribes this trend to a decrease in the Fe moment and an induced moment in the Ga that is antialigned to the Fe moment.