Magnetic coupling dependence on MgO interlayer thickness of FePt multilayered dots

L1(0)-ordered FePt (001) circular dot arrays with the FePt/MgO/FePt multilayered structure have been prepared and the relationship between the magnetic properties and the size of the dots or the MgO intermediate layer thickness has also been investigated. The dots were microfabricated from continuous films by electron beam lithography and Ar ion milling. The remarkable steps in the hysteresis loops for multilayer films with t(MgO) = 3, 5, 8, and 10nm indicated individual magnetization reversal of the top and bottom FePt layers. In the dots with t(MgO) = 3-8 nm, the step in the definition curves was not observed for D = 0.3 mu m(phi). When t(MgO) = 10 nm, remarkable step were observed not only for D = 0.5-3 mu m(phi) but also for D = 0.5 mu mf. (C) 2017 The Japan Society of Applied Physics