In-plane magnetized L10-FePt/permalloy (Py) bilayer films were prepared on an MgO (110) single crystal substrate, and their exchange-spring behavior was investigated. The FePt single layer deposited at the substrate temperature (Ts) of 300 C showed large uniaxial magnetic anisotropy in the in-plane direction. However, the coercivity (Hc) was reduced remarkably when the FePt layer of Ts 300 C was combined with the Py layer, resulting in no observation of exchange-spring behavior. By elevating Ts up to 450 C, on the other hand, Hc for the FePt layer was enhanced. Owing to the increase in Hc for Ts 450 C, spring back was definitely observed in the minor magnetization curves for the FePt/Py bilayers. This suggests the existence of the twisted magnetic structure in the Py layer. The dependence of exchange-spring behavior on the Py layer thickness was systematically examined. The experimental results were also discussed in comparison with numerical calculations.
ASJC Scopus subject areas
- Physics and Astronomy(all)