The effects of the thickness of magnetically hard- and soft-phase layers on magnetic properties and exchange coupling in multilayer magnets

The structure and magnetic properties of multilayer magnets containing a hard phase [HP≡ (Nd0.95Dy0.05)(Fe,Co,Nb,B) 5.5] and a soft phase (SP≡Fe and Fe65Co35) have been investigated. For the nanocomposite multilayer of Si(substrate)/Ti(30 nm)/[HP(x nm)/SP(y nm)] n/Ti(30 nm), the remanence enhancement has been observed at different thickness and volume fractions of hard- and soft-phase layers. The remanence increases and the coercivity decreases with the addition of soft phase, in comparison with the results of the single-layer film. For the multilayer of Si(substrate)/Ti(30 nm)/[HP(15 nm)/Fe(5 nm)] n/Ti(30 nm) annealed at 575 °C for 30 min, the coercivity of the multilayer reaches a maximum at n=20. Effects of the layer thickness and volume fraction of hard- and soft-phase layers on magnetic properties and exchange coupling in the multilayer films have been observed