Niu, Gang ; Hildebrandt, Erwin ; Schubert, Markus Andreas ; Boscherini, Federico ; Zoellner, Marvin Hartwig ; Alff, Lambert ; Walczyk, Damian ; Zaumseil, Peter ; Costina, Ioan ; Wilkens, Henrik ; Schroeder, Thomas (2014)
Oxygen Vacancy Induced Room Temperature Ferromagnetism in Pr-Doped CeO2 Thin Films on Silicon.
In: ACS Applied Materials & Interfaces, 6 (20)
doi: 10.1021/am502238w
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Integration of functional oxides on Si substrates could open a pathway to integrate diverse devices on Si-based technology. Oxygen vacancies (Vo··) can strongly affect solid state properties of oxides, including the room temperature ferromagnetism (RTFM) in diluted magnetic oxides. Here, we report a systematical study on the RTFM of oxygen vacancy engineered (by Pr3+ doping) CeO2 epitaxial thin films on Si substrates. High quality, mixed single crystalline Ce1–xPrxO2−δ (x = 0–1) solid solution films were obtained. The Ce ions in CeO2 with a fluorite structure show a Ce4+-dominant valence state in all films. The local crystal structures of the films were analyzed in detail. Pr doping creates both Vo·· and PrO8-complex defects in CeO2 and their relative concentrations vary with the Pr-doping level. The RTFM properties of the films reveal a strong dependence on the relative Vo·· concentration. The RTFM in the films initially increases with higher Pr-doping levels due to the increase of the F+ center (Vo·· with one occupied electron) concentration and completely disappears when x > 0.2, where the magnetic polaron concentration is considered to decline below the percolation threshold, thus long-range FM order can no longer be established. We thus demonstrate the possibility to directly grow RTFM Pr-doped CeO2 films on Si substrates, which can be an interesting candidate for potential magneto-optic or spintronic device applications.

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