STRUCTURE AND 100MHZ SOFT-MAGNETIC PROPERTIES IN MULTILAYERS AND GRANULAR THIN-FILMS

Recent developments in high-frequency magnetic thin films are overviewed. The topics discussed are multilayered nanocrystalline films and two-phase granular alloy films with high electrical resistivity. First, it is shown that Fe/Fe-Hf-C multilayers are promising high-frequency films with saturation magnetization Bs= 20kG and permeability mu'=6,000 up to 10 similar to 20MHz, which are at the highest levels among these types of magnetic thin films. Second, it is shown that (Fe,Co,Ni)-(Si,B,Zr etc.)-(F,O,N) granular alloy films posses uniquely high electrical resistivity rho as 10(3) similar to 10 mu Omega-cm together with high Bs of about 10kG, and consequently exhibit remarkable frequency dependence of mu' and loss mu '' up to 500MHz. These new-types of thin films are possible candidate materials for future high-frequency devices such as ''magnetic integrated circuits''. The properties are attributed to the two-phase granular structure, consisting of metallic grains and less conductive intergrains.