Coercivity change in an FePt thin layer in a Hall device by voltage application

The coercivity $(Hc)$ of a perpendicularly magnetized FePt layer was modulated by applying the voltage $(Vapp)$ to a Hall device through MgO and Al–O insulating layers. A change in $∼40Oe$ in $Hc$ was observed by changing $Vapp$ from −13 to 13 V. From the quantitative analysis of the voltage effect on $Hc$⁠, the change in the anisotropy energy by voltage application was evaluated to be 18.6 fJ/V m, which was of the same order as the theoretical prediction. The role of the MgO layer for the voltage effect was also discussed.