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Single-layer FePt (10 nm) film and trilayer FePt (10 nm)/Pt (t)/Fe (3 nm)/Pt (3 nm) (t = 0 nm, 0.5 nm, 1 nm, 2 nm and 4 nm) films were prepared on MgO (1 0 0) substrate. Their cross-sectional morphologies, ordering and interphase coupling behaviors were studied in detail. The results showed that the interphase coupling stiffness (J) increased at first, and then decreased with increasing thickness of the spacer layer. An exponential fitting of J ~ t dependence was obtained for t ≥ 1 nm. A discrepancy between experiments and exponential fitting, mainly caused by interfacial diffusion, was seen for t ≤ 1 nm. With respect to the proposed idea of using a spacer layer to modify the interface, FePt (8 nm)/Pt (0.5 nm)/Fe (3 nm)/Pt (3 nm) anisotropic nanocomposite film exhibited the best magnetic properties, with coercivity 0.87 T and (BH)max 370 kJ m−3, accounting for 95% of the theoretical (BH)max of L10-ordered FePt phase.

Recent advances in the study of exchange couplings in magnetic films are introduced. To provide a comprehensive understanding of exchange coupling, we have designed different bilayers, trilayers and multilayers, such as anisotropic hard-/soft-magnetic multilayer films, ferromagnetic/antiferromagnetic/ferromagnetic trilayers, [Pt/Co]/NiFe/NiO heterostructures, Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide (AAO) template. The exchange-coupling interaction between soft- and hard-magnetic phases, interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer, ferromagnetic layer, and antiferromagnetic layer. Some particular physical phenomena have been observed and explained.