Structural and Magnetic Characterization of Electrodeposited, High Moment FeCoNi Films

Abstract

We investigated the electrochemical deposition process of Fe-Co-Ni alloys from sulfate electrolytes containing no organic additives and the structural, magnetic, and electrical properties of the resulting films. The effect of pH and Co and Fe concentrations in the electrolyte on alloy composition is examined. The pH of the solutions is kept at 2.8 to minimize the incorporation of nonmagnetic matter. With increasing Ni content, a transition of the film structure from body-centered cubic (bcc) to face-centered cubic (fcc) is observed. X-ray diffraction and transmission electron microscopy results show that the smallest grain size of about 10 nm is obtained when the bcc and fcc phases coexist. Films with biphasic structure exhibit soft magnetic properties (coercivity about 1 Oe), high magnetic moment (about 2.1 T), narrow dispersion of the easy axis (less than 3°), and good high frequency response, with a resonance frequency above 1.8 GHz. Stress anisotropy has an important role in determining soft magnetic properties. © 2003 The Electrochemical Society. All rights reserved.