Synthesis of $L1-FePt$ perpendicular films with controllable coercivity and intergranular exchange coupling by interfacial microstructure control

A series of FePtBi/Au multilayers were fabricated by magnetron sputtering. The interfacial microstructure control of Bi and Au atoms and its effect on comprehensive properties of $L10-FePt$ perpendicular films were carefully studied. Results show that: perpendicular magnetic anisotropy of the $L10-FePt$ film can be remarkably enhanced with the epitaxial inducement of Au atoms. On the other hand, intergranular exchange coupling (IEC) of the film is greatly decreased due to the isolation of FePt particles by nonmagnetic Au particles. Moreover, the controllable coercivity of the film can be realized by adjusting ordering degree of the film through diffusion of Bi atoms. Thus, an $L10-FePt$ perpendicular film with controllable coercivity and no IEC is realized with the interfacial microstructure control of surfactant Bi and Au atoms.