Growth Mechanism of L10-Ordered FePt Epitaxial Thin Film

Atomic-level structures are investigated by high-resolution transmission electron microscopy (TEM) for 10 nm thick L1(0)-FePt thin films formed on MgO(001) substrate prepared under different conditions. TEM observation has shown that the lattice mismatch with MgO(9%) is decreased greatly by an introduction of misfit dislocation and by lattice bending in FePt material and that such disturbance in FePt crystal lattice is limited within a short distance of less than 2 nm from the MgO interface. Crystal lattice expansion in the lateral direction is recognized in an A1-FePt epitaxial film prepared at 200 degrees C through the lattice-level analysis of high-resolution TEM image. The lateral in-plane strain in FePt material associated with several factors, substrate, cap layer, and film morphology, is considered to have given a strong influence in promoting the growth of L1(0)-FePt(001) crystal and enhancing L1(0) ordering.