2009 Volume 50 Issue 3 Pages 664-670
Using a plasma-gas-condensation cluster deposition apparatus, Fe22Ni78 clusters are deposited on substrates. When a bias voltage, VA, is applied to a substrate, neutral and charged clusters are formed in a plasma region and hard-landed on the substrate, forming dense Fe22Ni78 cluster assembled films. For specimens prepared without introduction of O2 gas into a sputtering chamber (the oxygen flow rate, RO2=0 mol/s), the magnetic coercivity, HC, decreases, while the saturation magnetization, MS, increases as VA is increased up to 20 kV. The real part of magnetic permeability, μ′ is very small for VA=0 kV and it becomes a few hundreds for VA=5∼20 kV. For the dense Fe22Ni78 cluster-assembled films prepared at VA=20 kV with RO2≠0 mol/s, MS decreases, while the magnetic anisotropy field, HK, and the electrical resistivity, ρ, increase, and the ferromagnetic resonance frequency, fFMR, increases up to a frequency (f) range of GHz. There are two magnetically optimized states: (1) μ′=760 at f=10 MHz for the specimen prepared at VA=20 kV with the oxygen flow rate, RO2=0 mol/s and the Ar flow rate, RAr=4.5×10−4 mol/s, and (2) μ′=370 at 10 MHz and fFMR=1.10 GHz for the one prepared at VA=20 kV with RO2=3.7×10−8 mol/s and RAr=4.5×10−4 mol/s.