Morphology evolution and magnetic properties improvement in FePt epitaxial films by in situ annealing after growth

This paper presents a detailed study of structure, morphology, and magnetic properties in FePt thin films epitaxially grown on MgO(100) at intermediate temperatures (≅380°C). It focuses on the effects obtained by in situ annealing the FePt films after deposition. We have demonstrated that the annealing allows one to complete the ordering, thus obtaining an epitaxial L10-FePt film with large perpendicular anisotropy (up to 3×107erg∕cm3) and high perpendicular squareness and remanence ratio (both higher than 0.85). At the same time, we have found a peculiar morphology evolution by increasing the annealing time: the interconnected mazelike grains evolve towards interconnected dotlike grains of reduced size (down to 10nm). Due to the interconnection at the grains basis, the increase in the film perpendicular coercivity with the annealing process is moderate (up to 4.1kOe), leading to an increasing anisotropy/coercivity ratio with the annealing time. As a further step towards the understanding of the propertie...