A study of complex permeability in rare earth-substituted cobalt/nonmagnetic transition metal amorphous thin films

Abstract

By using radio-frequency (rf) sputtering, amorphous ferromagnetic thin films of composition (Co93Zr7)100−yREy (RE=Nd, Pr, Dy, Tb, Gd, or Sm: magnetic rare earth elements) have been prepared. This work was performed for small amounts of RE substitution (y<3). These films exhibit static soft magnetic properties similar to CoZr alloys. For all compositions studied, a low in-plane uniaxial anisotropy Hk appears, whose magnitude depends upon composition and preparation parameters. Above a critical substitution level, a biaxial anisotropy exhibiting an in-plane Hk and a perpendicular component Hp is measured for films containing Gd or Sm. The substitution by RE atoms essentially affects the frequency-response shape of complex permeability, depending on nature, concentration of RE atoms and on values of both Hk and Hp. High-frequency permeability spectra could be well fitted by a theoretical model based on magnetization changes due to rotation, using a composition-dependent Landau–Lifshitz damping term. The results on films exhibiting uniaxial or biaxial anisotropy are reported and discussed.

Dependence of soft magnetic properties and high frequency characteristics on film thickness for Ni75Fe25–ZnO nano-granular films

“…For the typical sample with t = 500 nm, it is seen that is more than 110 below 1.0 GHz, while the imaginary part is much smaller than , which indicates that the film can be the potential materials applied on sensors operated in high frequency range. The increases to a maximum at f = 1.65 GHz, which can be ascribed to the ferromagnetic resonance FMR, the FMR frequency is stated as [11,18]:…”

Recovery of soft magnetic properties of FeNiSm films by Ta interlayer

“…It can be seen that the calculated and experimental spectra are consistent using damping constants a of 0.22 and 0.25, respectively, for the 100 nm FeNiSm film and the 200 nm FeNiSm film with one 6 nm Ta interlayer. The broadened resonance peak widths may result from the high damping constants due to the rare-earth element doping [20,28].…”

Fabrication, magnetism and high frequency application of exchange-coupled Fe65Co35±2–SiO1.7±0.2 granular films

“…Since the magnetic crystalline anisotropy of individual particles is averaged, an in-plane uniaxial anisotropy was induced by applying an external field during deposition. So the behaviour of magnetization in high frequency magnetic field can be described by the Landau-Lifshitz and FMR frequency [24] is stated as:…”