Ultrasoft magnetic properties of Co-Fe-Hf-O nanocomposite films

This paper reports on the excellent high-frequency magnetic performance of Co-Fe-Hf-O thin films, which were deposited on Si(100) substrates by the oxygen reactive rf-sputtering method. It was shown that the films possessed not only high electrical resistivity but also large saturation magnetization and hard-axis anisotropy field. Among the compositions investigated, Co19.35Fe53.28Hf7.92O19.35 exhibited the ultrasoft magnetic properties of high saturation magnetization, 4πMs∝19.86 kG, and low coercivity, Hc∝1.5 Oe. The magnetic permeability remained almost constant up to 3 GHz and reached a maximum at the ferromagnetic resonant frequency of 4.024 GHz. These properties of this film together with a high electrical resistivity of 3569 μΩcm make it ideal for producing micromagnetic devices for high-frequency applications. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)