<i>In situ</i> ordered polycrystalline FePt L10 (001) nanostructured films and the effect of CrMn and Zn top layer diffusion

Abstract

The nanostructure and magnetic properties of in situ ordered polycrystalline FePt thin films (9 nm) have been studied. Films were deposited with a MgO underlayer onto Si and glass substrates using conventional rf diode sputtering. Perpendicular anisotropy was obtained when the substrate temperature exceeded 490 °C. The maximum order parameter (S) was estimated to be ∼0.9. The coercivities (Hc) ranged from 5 to 12 kOe. Observed high values of the coercive squareness (S*) indicate the existence of exchange coupling. High resolution transmission electron microscopy indicates a defective region which might be associated with defect-related localized incoherent nucleation, thereby inducing low values of Hc. Zn and CrMn top layers at ambient temperature were deposited after the deposition of FePt films at elevated temperatures. Rapid thermal annealing of these samples at 180–450 °C for 1 min resulted in a decrease of S* from 0.8–0.85 to ∼0.5–0.6.