Microstructure and Magnetic Properties of In-Situ Deposited $L1_{0}$ FePt Films on MgO(200) Films of Varying Thicknesses

The FePt(30 nm)/MgO bilayer films with various MgO(200) underlayer thicknesses of 0 to 30 nm are in-situ deposited on Si substrates. A weak (111)_FePt peak as well as strong (001)_FePt and (002)_FePt peaks are observed in XRD pattern of single-layered FePt film with no MgO underlayer. When a 5 nm thick MgO film is introduced under the FePt film, the (111)_FePt peak almost disappears and both the (001)_FePt and (002)_FePt peaks are enhanced greatly. This indicates that the perpendicular magnetic anisotropy of FePt film can be improved by introduction of a thinner MgO underlayer. However, a weak (111)_FePt peak appears again as the MgO underlayer is increased to 10 nm, revealing that the perpendicular magnetic anisotropy of FePt film will be deteriorated by introducing a thicker MgO underlayer.