The electronic structure of single-crystalline EuO (100) ultrathin films, together with their exchange splitting energy (ΔEEX) and ferromagnetic phase transition temperature (TC), was investigated by temperature- and thickness-dependent angle-resolved photoemission spectroscopy. Both ΔEEX and TC decreased monotonically with decreasing film thickness. The band shift showed an opposite thickness dependence at the Γ and X points, reflecting the balance of the hybridization between the Eu 4f and O 2p states (super-exchange interaction) and between the Eu 4f, O 2p, and Eu 5d states (indirect-exchange interaction). The observed transition from an indirect energy gap in the bulk to a direct gap in the ultrathin films of the ferromagnetic semiconductor EuO could be potential in future spintronic devices.
CITATION STYLE
Miyazaki, H., Hajiri, T., Matsunami, M., Inukai, M., Ito, T., & Kimura, S. I. (2022). Observation of Thickness-Dependent Exchange Interaction in EuO Ultrathin Films. Frontiers in Nanotechnology, 4. https://doi.org/10.3389/fnano.2022.872717
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