Frequency-dependent complex permeability in Zr-substituted permalloy thin films

Summary form only given. It is well known that the gyromagnetic resonance frequency of ferromagnetic thin films, with in-plane uniaxial anisotropy, has a direct dependence on the anisotropy field and the saturation induction. Many works have been devoted to the effect of the anisotropy field on the dynamic permeability spectra. Low resonance frequencies are achieved involving a multi-layer structure with an undercoat. In this work, we investigate Zr-substitution in permalloy thin films in order to control the magnetic properties and then to tune the resonance frequency at lower values. The (Ni/sub 80/Fe/sub 20/)/sub 1-x/Zr/sub x/ thin films are deposited onto glass substrates by rf sputtering with a dc magnetic field applied along the film plane, without post-annealing. The structural transition from a crystalline to an amorphous phase, saturation induction, in-plane anisotropy, electrical resistivity and frequency-dependent permeability are studied for the Zr content ranging from 0 to 17 % at. In this paper, we focus on the measurements performed on 2000 /spl Aring/ thick films of the resistivity versus Zr-concentration using a four-point probe and the complex permeability using a permeameter. The results clearly exhibit a linear variation of the resistivity of (Ni/sub 80/Fe/sub 20/)/sub 1-x/Zr/sub x/ thin films with the Zr content. A resistivity of 260 /spl mu//spl Omega/.cm is obtained for x=17 % at. The high-frequency permeability is first measured on these materials which were mainly studied for magnetoresistive applications. The authors show that the permeability is drastically affected by the Zr-substitution with a significant shift of the resonance frequency from 600 to 300 MHz which correlates with the decrease of the saturation induction from 10500 to 2100 G.