Stabilization of perpendicular magnetic anisotropy in CeO2 films deposited on Co/Pt multilayers

Abstract

Materials with perpendicular magnetic anisotropy (PMA) are of great interest as they have potential applications in high-density non-volatile memories, spin logic devices, and other spintronics applications. To attain perpendicular anisotropy, a number of material systems have been explored as ferromagnetic electrodes. Here, we use (Co/Pt)-multilayered films with PMA covered by a gold spacer-layer to induce the perpendicular magnetization in a ferromagnetic layer of cerium oxide and to control the reversible switching of its magnetization. The origin of the room-temperature ferromagnetism observed in nanocrystalline cerium oxide films remains controversial, but their wide energy band-gap and their transparency to visible light attracts attention for possible applications in magneto-optical devices. A weak magnetic stray field of 40 Oe emanates from the (Co/Pt)-multilayered film and permeates the gold spacer layer. Using a simple micromagnetic model based on the Stoner–Wohlfarth magnetization mechanism, the strength of the magnetic coupling between the ferromagnetic layers is estimated to be 18 μJ m⁻². This magnetic coupling, which is almost independent of temperature, is sufficient to promote the reversible switching of perpendicular magnetization states in the field range of a only few hundred Oersteds at room temperature.