Soft magnetic properties and microstructure of Fe65Co35 thin films with different underlayers

High-moment soft magnetic Fe65Co35 thin films with well in-plane uniaxial anisotropy were obtained by cosputtering on Co93Fe7, Ni80Fe20 Cu and Fe underlayers. The single-layer Fe65Co35 film with thickness of 100 nm shows a magnetic anisotropy. The coercivity along easy axis H-ce and that along hard axis H-ch are equal to 3.3 kA/m and 2.1 kA/m, respectively. The soft magnetic properties of Fe65Co35 films were much improved by using an underlayer. The H-ce and H-ch of Fe65Co35 films with Ni80Fe20, Co93Fe7, and Cu underlayers can be reduced to 0.9- 1.1 kA/m and 0.08-0.20 kA/m, respectively. For films with Fe underlayer, the H-ce and H-ch reduced to 1.1 kA/m and 0. 6 kA/m, respectively. In the case of Co93Fe7, Ni80Fe20 and Fe underlayers, the coercivity of films did not depend remarkably on the thickness t of underlayer at t > 1 nm. While in the case of Cu underlayer, the coercivity of films changed remarkably with increasing underlayer thickness. It was shown that the texture of double-layered underlayer/Fe65Co35 films is dependent on the material and the thickness of underlayer. The influence of the underlayer on the surface morphology and micro-magnetic structure of films were investigated by AFM and MFM. It was suggested that the modification of the structure of Fe65Co35 films by using an underlayer is an important way to improve their soft magnetic properties. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.