| The near-stoichiometric Ll0 phase FePt alloy with Ku～7×107 erg/cm3 is considered to be one of the most promising candidates for high density PMR media as the magnetization energy barrier in a grain as small as～3 nm is enough to overcome thermal instability. In this thesis, we have deposited FePt films on MgO(001) substrates by magnetron co-sputtering to investigate the (001) orientated and continous control of the Llo-FePt thin film. The spontaneous magnetization and the magnetization reversal of single-domain particles were stimulated by micromagnetic method; The continuity of film in high temperature enviorment was also analyzed.FePt thin films were deposited on MgO(001) substrates heated to 700℃by magnetron co-sputtering. Assisted by the misfit of lattice between film and substrate, strong (001) texture was formed. The film at tN= 5 nm was composed of nanoparticles with a size of～70 nm (smaller than the critical size of single-domain particle), and showed a high coercivity of～105 kOe at 4.2 K. The morphology can be adjusted obviously by the thickness, but the perpendicular magnetic coercivity changed slowly as the thichness tN less than 45 nm. After tN is more than or equal to 50 nm, the film changed from discontinuous to maze-like, the coercivity dropped about one order of magnitude, implying that a high Hc was mainly contributed to by discontinuity of the film, instead of by presence of the single-domain particles. Micromagnetic simulation implies that the magnetization reversal of a separated single-domain Llo-FePt nanoparticle with size of 70 x 70 x 5 nm3 is a vortex-like nuclear type. Its ideal coercivity is～121 kOe. This tells us that the experimental coercivity had nearly reached the limit of ideal single crystalline nanoparticles.In order to overcome the discontinuity, films with a multilayer structure of [Fe(0.6 nm)/Fe3o.5Pt69.5(1.9 nm)]10 (the total composition was Fe5opt5o) were deposited on MgO(001) substrates heated to 400℃by a high-vacuum multi-target magnetron sputtering system and then subjected to a vacuum annealing at temperatures in the range of [500,900]℃. Accoreding to XRD patterns, for the as-deposited film, only the (200) peak attributed to disordered A1 FePt texture can be seen. This indicates that the interlayer diffusion occurred, but not formed ordered phase. For the films annealed at 700℃indicated the presence of textured LI0 phase which is shown by the onset of (001) and (003) reflections from superlattice in addition to the FePt (002) fundamental peak, and its magnetocrystalline anisotropic energy was larger than 2.5x107 erg/cc. The morphology observed by a scanning electron microscopy (SEM) found that these films obtain continuous as the annealing temperature less than 800℃. It was attempted to give an explanation to the physical mechanism of these phenomena from thermodynamic point. The migration of atoms along perpendicular direction in compositional gradient films might suppress the segregation of Pt and sufficiently avoid discontinuity due to Pt richment at grain boundaries in phase transformation.
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