Electrodeposition of granular FeCoNi films with large permeability for microwave applications

Abstract

A simple methodology to fabricate soft magnetic FeCoNi granular films from cheap salt solutions viaelectrodeposition at room temperature is demonstrated. With the addition of a small quantity of organic and inorganic additives into the solutions, the FeCoNi nano-granular films possess ultra-high permeability, large resistivity, and other desirable magnetic properties for gigahertz microwave applications. Typically, the films have a coercivity of less than 10 or 20 Oe along the hard or easy axis, respectively, with a saturation flux density of up to 2.43 T. The magnetic permeability and resistivity are correspondingly up to a magnitude order of about 10³ and 10⁻⁴ Ω cm. These soft FeCoNi films also show a big anisotropic field of more than 50 Oe and a very small magnetostriction of <10⁻⁵. They can be potentially applied to microwave absorption as well as other applications.