Soft Magnetic Properties of High-Resistive CoBN/AlN Multilayers.

The magnetic and structural properties of multilayered CoBN/AIN films prepared by sputtering Were investigated, With the intention of creating suitable films for application to micromagnetic devices operating at high frequency. A CoBN single layered film has ρ of about 340μΩcm, Bs of about 10.3kG, and perpendicular magnetic anisotropy. CoBN/AIN multilayers, even where the thickness of the AIN layer is around 3Å, exhibit soft magnetic properties (Hc<1 Oe and μ>500) in a wide range of combinations of film thicknesses of both layers. SEM observation suggests that the soft magnetic properties of the multilayers originate in their in-plane uniaxial anisotropy and fine grains in the CoBN. The magnetostriction of multilayers ranges between-1 and +1×10-6, and their anisotropic field is over 15 Oe. Although the film thickness exceeded 2μm, μ was maintained, even at a frequency close to 300MHz.