Abstract
The magnetic anisotropy and magnetic interactions at the interface between and (001) were investigated. Depending on the growth conditions of the (001) layers and the postannealing temperature, the preferential magnetization direction of the ultrathin layer grown on a (001) layer changed from the in-plane direction to a direction perpendicular to the film plane. The lattice constant of the (001) layers parallel to the growth direction increased with flow rate, while that parallel to the in-plane direction were locked onto the MgO(001) substrate regardless of the growth conditions of the NiO layers. Moreover, perpendicular magnetization was observed only when the NiO layer was grown with flow rates higher than 2.0 sccm corresponding to oxygen-rich NiO. X-ray magnetic circular dichroism measurements revealed an enhancement in anisotropic orbital magnetic moments similar to the origin of perpendicular magnetic anisotropy at the /MgO(001) interface. The interfacial magnetic anisotropy energies were 0.93 and at room temperature and at 100 K, respectively, indicating less temperature dependence. In contrast, the coercivity exhibited a significant temperature dependence. Although no signature of exchange bias or unidirectional loop shift was observed, was strongly dependent on the NiO layer thickness, indicating that the exchange interaction at the interface between the ferromagnetic and antiferromagnetic layers was not negligible, despite the NiO(001) being a spin-compensated surface.
- Received 28 October 2022
- Revised 4 February 2023
- Accepted 28 April 2023
DOI:https://doi.org/10.1103/PhysRevApplied.19.064005
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