Composition, structure, stress, and coercivity of electrodeposited soft magnetic CoNiFe films - Thickness and substrate dependence

The properties of soft magnetic CoNiFe films electrodeposited in the presence of saccharin and sodium lauryl sulfate additives were studied in terms of their thickness and substrate dependence. Auger depth profile analysis of the elemental composition in CoNiFe films electrodeposited over different substrates (Pd90Ni10, 1.0 T NiFe, Cu) demonstrate that the average composition at the substrate interface and bulk deposited films remains constant. X-ray diffraction (XRD) measurements reveal the existance of mixed fcc + bcc phase with larger amounts of bcc crystallites near the substrate side of the films, i.e., at the lower thickness. XRD and transmission electron microscopy measurements revealed a larger grain size at the CoNiFe/substrate interface. The measured average stress is both substrate- and thickness-dependent. The easy-axis coercivity, H-c, follows the Neel's relation H-c = ct(n) (t is the thickness and c is a constant). It was found that the value of the exponent n is substrate dependent. Mechanisms related to the coercivity of CoNiFe films deposited over different substrates (1.0 T NiFe, Cu, Pd90Ni10, high magnetic moment CoNiFe) are discussed in terms of material properties of these magnetic films. (C) 2001 The Electrochemical Society.