The effect of annealing on the magnetic properties of permalloy films in permalloyTa bilayers

Abstract

The reaction between permalloy and Ta bilayer thin films annealed at 100 to 450°C, and the effects of sputtering order of permalloyTa bilayer thin films on the magnetic properties of the permalloy layer have been investigated. The interdiffusion onset temperature between permalloy and Ta in Ta/permalloy bilayer thin films is lower than that in permalloy/Ta bilayer films. The coercivity of the permalloy layer increases and the magnetostriction changes towards positive values due to the preferential diffusion of Ni from the permalloy layer into the Ta layer. The average grain diameters of permalloy layers are approximately 5 nm for glass substrate and 10 nm for Ta substrate. This is thought to be due to the difference in chemical affinity between glass and Ta substrates. The difference between the average grain diameters is the main cause of the difference in interdiffusion.