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 similar to 0.9. Very narrow X-ray rocking curves (FWHM < 1 degrees) 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 degrees\ peak at a photon energy of 2,0 eV (630 nm wavelength) in the polar magnetooptical Kerr rotation theta(K) spectrum, which does nob agree with that of the polycrystalline FePt ordered alloy.