Abstract: FePt(50nm) and [FePt(2,3,5nm)/AlN(1nm)]_n films were prepared by RF magnetron sputtering technique, then annealed at 550℃ for 30min. The effect of the number of bilayer repetitions (n) and AlN content on
structure and magnetic properties of various FePt/AlN multilayers was studied. The highest coercivity and squareness of FePt/AlN multilayers annealed at 550℃ were obtained for n=8. The grain size of the FePt/AlN
films by post-annealing increases with increasing n. Introducing the nonmagnetic AlN not only hinders the growth of FePt particles, but also reduces the intergrain exchange interactions of the FePt/AlN films. And the
interactions are decreased as AlN content is increased. Grain size (V_grain) has almost the same size as magnetic activation volume (V*) due to the addition of AlN in films by post-annealing.

Key words: FePt/AIN thin film, coercivity, activation volume, exchange interaction