Preparation of FePt(001) Epitaxial Perpendicularly Magnetized Thin Films and Their Magnetic Properties

Abstract

Epitaxial FePt(001) thin films were prepared on MgO(100) substrates by RF-magnetron sputtering. Magnetization measurements revealed that all the samples were more easily magnetized by a field applied perpendicular to the film plane than by one applied parallel to it. The square-ness M_r/M_s improved with decreasing FePt layer thickness d_FePt; this is considered to be due to a change in the magnetic domain structure. Pt buffer layers were also found to be effective for improving the magnetic properties. The maximum energy product (B·H)_max a sample with d_Pt=1000Å grown on a polished substrate had a maximum value of 30 MG-Oe This effect of the Pt buffer layer on the magnetic properties is sensitive to the surface condition of the substrate.