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Oxygen Vacancy Induced Room Temperature Ferromagnetism in Pr-Doped CeO2 Thin Films on Silicon

Niu, Gang and Hildebrandt, Erwin and Schubert, Markus Andreas and Boscherini, Federico and Zoellner, Marvin Hartwig and Alff, Lambert and Walczyk, Damian and Zaumseil, Peter and Costina, Ioan and Wilkens, Henrik and Schroeder, Thomas (2014):
Oxygen Vacancy Induced Room Temperature Ferromagnetism in Pr-Doped CeO2 Thin Films on Silicon.
In: ACS Applied Materials & Interfaces, ACS Publications, pp. 17496-17505, 6, (20), ISSN 1944-8244, [Online-Edition: http://dx.doi.org/10.1021/am502238w],
[Article]

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.

Item Type: Article
Erschienen: 2014
Creators: Niu, Gang and Hildebrandt, Erwin and Schubert, Markus Andreas and Boscherini, Federico and Zoellner, Marvin Hartwig and Alff, Lambert and Walczyk, Damian and Zaumseil, Peter and Costina, Ioan and Wilkens, Henrik and Schroeder, Thomas
Title: Oxygen Vacancy Induced Room Temperature Ferromagnetism in Pr-Doped CeO2 Thin Films on Silicon
Language: English
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.

Journal or Publication Title: ACS Applied Materials & Interfaces
Volume: 6
Number: 20
Publisher: ACS Publications
Uncontrolled Keywords: ferromagnetism, oxides, thin films, oxygen vacancies, doping
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
Date Deposited: 17 Nov 2014 13:34
Official URL: http://dx.doi.org/10.1021/am502238w
Identification Number: doi:10.1021/am502238w
Funders: Dr. Gang Niu gratefully acknowledges funding support by Alexander von Humboldt foundation in form of an AvH Post-Doc fellowship., This work is partly supported by “ Deutsche Forschungsgemeinschaft ” (DFG).
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