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

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), pp. 17496-17505. ACS Publications, ISSN 1944-8244,
[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 ; Hildebrandt, Erwin ; Schubert, Markus Andreas ; Boscherini, Federico ; Zoellner, Marvin Hartwig ; Alff, Lambert ; Walczyk, Damian ; Zaumseil, Peter ; Costina, Ioan ; Wilkens, Henrik ; 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
Journal 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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