Magnetic Properties of Multilayer Permalloy Films Prepared by Evaporation

The magnetic properties of Permalloy single-layer films and multilayer films with SiO2 intermediate layers, prepared by evaporation, were investigated. Single-layer films of thicknesses ranging from 1 to 4 m had a high coercivity of 5 to 8 Oe and a low permeability of 300 to 400. The magnetic properties of multilayer films depended on the thickness of the SiO2 layers. Excellent soft magnetic properties (Hch=0.6 Oe, ¿´=2500 at 0.5 to 10 MHz) were obtained at an SiO2 thickness of 150 Ã…. SEM observations revealed that the SiO2 thickness must be greater than 150 Ã… to prevent columnar growth and the formation of grain boundaries in the magnetic layers.