Epitaxial Fe3Pt/FePt nanocomposites on MgO and SrTiO3

We have exploited the pseudomorphic growth of the magnetically soft Fe3Pt phase on top of L10- FePt to obtain fully epitaxial soft/hard nanocomposites on both MgO(100) and SrTiO3(100). The magnetic properties of this new nanocomposite system, driven by the soft/hard exchange- coupling, can be tailored by varying soft phase thickness, soft phase magnetic anisotropy and substrate. Coercivity is strongly reduced by the addition of the soft phase, a reduction which is definitely affected by the nominal composition of the soft phase and by the substrate choice; similarly is the magnetic phase diagram of the composite system. Coercive field decreases down to 21% of the hard layer value for Fe3Pt(5 nm)/FePt(3.55 nm) nanocomposites on SrTiO3; this maxi- mum coercivity reduction was obtained with a nominal atomic content of Fe in the soft phase of 80%.