Giant induced magnetic anisotropy In strain annealed Co-based nanocomposite alloys

Abstract

Low loss switching of soft magnetic materials at high frequencies benefits from tuning the induced anisotropy. We show induced anisotropies,K_u, as large as 1.89×10⁴ J/m³, developed by strain annealing of Co-rich nanocompositealloys. Crystalline phases in this alloy system have large negative magnetostrictive coefficients, leading to anisotropy fields per unit stress over twice those developed in FINEMET. Tunable permeability and reduced thicknesses achieved in this process can mitigate eddy-current losses. Giant induced magnetic anisotropies are discussed in light of models for the micromechanisms of amorphous metal deformation, stress-assisted transformations in the crystallites, and directional pair ordering.