Perpendicular Magnetization of Epitaxial FePt(001) Thin Films with High Squareness and High Coercive Force

Perpendicular magnetized epitaxial FePt(001) thin films were prepared by RF-magnetron sputtering. The long range order parameter S of the FePt layer was found to be ∼0.9. Very narrow X-ray rocking curves ( FWHM<1°) of the FePt(002) and Pt(200) peaks indicate that both layers are essentially single crystalline. With increasing Pt buffer layer thickness d Pt , the squareness M r / M S and coercive force H C were found to increase to 100% and 7.2 kOe, respectively. The FePt(001) thin film has a |0.58°| peak at a photon energy of 2.0 eV (630 nm wavelength) in the polar magnetooptical Kerr rotation θ K spectrum, which does not agree with that of the polycrystalline FePt ordered alloy.