Microstructure and magnetic properties of FePt and Fe/FePt polycrystalline films with high coercivity

We have investigated the microstructure and the magnetic properties of FePt and Fe/FePt polycrystalline thin films with high coercivity. The L1(0) FePt particulate film deposited on a heated amorphous SiO2 substrate showed a large coercivity (H-c) as high as 23 kOe. Contrary to an epitaxially grown single crystal FePt film, the H-c did not show a drastic decrease when the film morphology changed from particulate to continuous. The polycrystalline film with a thickness of 100 nm exhibited a coercivity of 13 kOe in spite of its simple processing route. This high coercivity is attributed to the magnetic domain pinning at the grain boundaries. By depositing Fe layers on the particulate FePt films, an increase of remanence and energy product was observed as a result of the exchange coupling of the Fe and FePt layers. (C) 2004 American Institute of Physics.