Influence of the buffer layers on magnetic properties of FePt(001) films sputter-deposited at reduced temperature

The magnetic properties of Fe38Pt62 and Fe52Pt48 films sputter deposited on MgO (001) substrates with and without a buffer layer at the substrate temperature T-s of 300 degreesC have been investigated. Pt, Au, and PtAu alloys with different compositions were used as the buffer layer to study the influence of the lattice mismatch between the FePt layer and the buffer layer. The L1(0) ordered structure with large perpendicular magnetic anisotropy has been obtained for the Fe38Pt62 films irrespective of the buffer layer. The degree of long-range order S and uniaxial magnetic anisotropy energy K-u increase with increasing the lattice mismatch, and S and K-u show maxima of 0.8+/-0.1 and 2.7x10(7) erg/cm(3), respectively, for the film without a buffer layer. For Fe52Pt48 films, on the other hand, the L1(0) ordered structure with perpendicular magnetic anisotropy has been obtained only for the film with an Au buffer layer. (C) 2004 American Institute of Physics.