Rise and fall of ferromagnetism in O-irradiated Al2O3 single crystals
In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al2O3 single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry...
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Veröffentlicht in: | Journal of applied physics 2015-06, Vol.117 (23) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al2O3 single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The ferromagnetism rise and fall during the process of annealing-oxygen irradiation-annealing of the sapphire. The ferromagnetic changes are consistent with Al-vacancy related defects detected by positron annihilation spectroscopy. With first-principle calculations, we confirm that Al-vacancy can introduce magnetic moment for 3 μB in Al2O3 crystal and form stable VAl-VAl ferromagnetic coupling at room temperature. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.4922788 |