Magnetic and microwave properties of ion-beam-sputtered amorphous FexCo80−xB15Si5 films

Abstract

Magnetically soft amorphous films of FexCo80−xB15Si5 (x=0, 6, 23, 40, 70, 80) were ion beam sputter deposited onto fused quartz for static and microwave magnetic characterization. Films ranged in thickness from 220 to 260 nm and were deposited at rates of 0.1–0.2 nm/s. Saturation magnetization, coercivity, and loop squareness values were extracted from hysteresis loops generated by a vibrating sample magnetometer. Ferromagnetic resonance measurements were taken using a 9.5-GHz cavity with the applied magnetic field both parallel and perpendicular to the plane of the film, yielding values for the g factor, anisotropy field, effective magnetization, and linewidth. Well resolved quadratic spin-wave resonance spectra allowed for the deduction of exchange stiffness constants. Hysteresis loops showed well-defined uniaxial in-plane anisotropies for Fe-rich films, with easy axis loop squareness decreasing with decreasing Fe content. Saturation magnetization and effective magnetization values were found to reach a maximum at x=70 for those compositions investigated. These films were found to have soft magnetic properties comparable to the FexNi80−xB15Si5 alloy films previously investigated.