No abstract

No abstract

Electrically insulated ferrous powders permit isotropic magnetic flux, lower core losses, and structural freedom for state-of-the-art electromagnetic (EM) core and device designs. Many current coating materials are limited by low melting temperatures, which leads to insu cient insulation of powders, resulting in metal-on-metal contact. Use of a high-temperature coating material, such as alumina, could alleviate these issues. In this work, iron powder was mechanically milled with alumina media, to yield plastically deformed, alumina-coated iron particles with improved magnetic saturation, elastic modulus, and hardness. Various milling times and media ball sizes are investigated to maintain particle size, insulate powders uniformly, and optimize properties after compaction and curing. We found that longer milling times yielded more dense powder coatings and lower magnetic saturation.

No abstract

The soft magnetic and microwave properties of amorphous FeCoNbBCu thin films with thicknesses varying from 70 nm to 450 nm have been systematically investigated. Due to the amorphous structure, the coercivity is 1.5 Oe in thicker films. The thickness-dependent microwave characteristics of the films were measured over the range 0.5–6 GHz and analyzed using the Landau–Lifshitz–Gilbert equation. Without applying magnetic field during deposition and measurement, an in-plane uniaxial anisotropy in amorphous thin films was obtained, ranging from 21 to 45 Oe. The interface interaction between substrate and film is confirmed to be the origin of the induced anisotropy, whereas the volume anisotropy contribution is more pronounced with increasing film thickness. For films possessing an in-plane uniaxial anisotropy, the shift of resonance frequency with thickness is observed and verified by the Kittel equation. The demonstration of a controllable and tunable anisotropy suggests that the FeCoNbBCu thin films have potential application as magnetic materials for Spintronics-based microwave devices.