ODMR and EPR investigations of Fe centers in KTaO3

Autor(en): Reyher, HJ
Faust, B
Maiwald, M
Hesse, H
Stichwörter: CRYSTALS; DETECTED MAGNETIC-RESONANCE; IMPURITIES; IONS; NOMINALLY PURE KTAO3; Optics; Physics; Physics, Applied; SITES; SPECTRA
Erscheinungsdatum: 1996
Herausgeber: SPRINGER VERLAG
Journal: APPLIED PHYSICS B-LASERS AND OPTICS
Volumen: 63
Ausgabe: 4
Startseite: 331
Seitenende: 337
Zusammenfassung: 
The analysis of EPR spectra obtained from iron doped KTaO3 crystals in the as-grown state revealed three dominant iron centers: Fe3+-O-I, axial Fe-centers with spin S = 3/2 and rhombic Fe3+. By comparison with data from literature possible assignments for the center with S = 3/2 are discussed. For the rhombic species the temperature dependence of the main parameters of the Spin- Hamiltonian was measured. The result makes it most plausible that only one rhombic iron center exists in KTaO3, in contrast with literature. The understanding of the EPR spectra allows us to assign transitions, observed at very low magnetic fields by optically detected magnetic resonance (ODMR), to this rhombic Fe center. On this basis, the magnetic circular dichroism (MCD) of this defect could be identified using the method of tagged-MCD. This spectrum is compared to the tagged-MCD of Fe3+-O-I and of axial Fe4+ centers, which may be generated metastably by optical charge transfer. Considerably different structures in the MCD spectra of both Fe3+ centers indicate different local surroundings and electronic states.
ISSN: 09462171

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