High Frequency Magnetic Property of Dense Fe22Ni78 Cluster Assembled Films

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 1⁄4 0mol/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, 0 is very small for VA 1⁄4 0 kV and it becomes a few hundreds for VA 1⁄4 5 20 kV. For the dense Fe22Ni78 clusterassembled films prepared at VA 1⁄4 20 kV with RO2 61⁄4 0mol/s, MS decreases, while the magnetic anisotropy field, HK, and the electrical resistivity, , increase, and the ferromagnetic resonance frequency, fFMR, increases up to a frequency ( f ) range of GHz. There are two magnetically optimized states: (1) 0 1⁄4 760 at f 1⁄4 10MHz for the specimen prepared at VA 1⁄4 20 kV with the oxygen flow rate, RO2 1⁄4 0mol/s and the Ar flow rate, RAr 1⁄4 4:5 10 4 mol/s, and (2) 0 1⁄4 370 at 10MHz and fFMR 1⁄4 1:10GHz for the one prepared at VA 1⁄4 20 kV with RO2 1⁄4 3:7 10 8 mol/s and RAr 1⁄4 4:5 10 4 mol/s. [doi:10.2320/matertrans.MER2008374]