Photoinduced EPR in KTa0.988Nb0.012O3 crystals
Abstract
We report the first experimental observation of the photoinduced EPR spectra in KTa1-xNbxO3 crystals (x = 0.012). The signal has two components: nearly isotropic with geff = 2 and strongly anisotropic one. Isotropic signal originates most probably from single localized photo-carriers - electrons or holes. Anisotropic spectrum is observed below 10 K and reveals a set of characteristic properties. It originates from the axial centers with axes coinciding with the C4 axes of the crystal. Effective g-factor values are gparallel = 2.106(3) and gnormal < 0.8. Angle dependencies of the intensity and the width of the anisotropic signal as well as the resonance field can qualitatively be explained within the simple J = 1 model. The observed anisotropic photoinduced EPR spectrum is tentatively assigned to excitons or bipolarons.
Supporting agencies: This work was supported by the RNP-6183 project of the Russian Ministry of Education and Science, Grant KAN 301370701 of the AS CR, AV0Z10100522, Sc.Sch.-2628.2008.2.
About the Authors
A. I. Gubaev
Basel University
Switzerland
Switzerland
Klingelbergstr. 50-70, Basel 4056
A. A. Rodionov
Kazan State University
Russian Federation
Russian Federation
Kremlevskaya, 18, Kazan 420008
M. Kh. Salakhov
Kazan State University
Russian Federation
Russian Federation
Kremlevskaya, 18, Kazan 420008
I. N. Subacheva
Kazan State University
Russian Federation
Russian Federation
Kremlevskaya, 18, Kazan 420008
P. P. Syrnikov
A. F. Ioffe Physical-Technical Institute
Russian Federation
Russian Federation
St.-Petersburg 194021
V. A. Trepakov
A. F. Ioffe Physical-Technical Institute; Institute of Physics, ASCR
Russian Federation
Russian Federation
St.-Petersburg 194021; 182 21 Prague 8, Czech Republic
R. V. Yusupov
Kazan State University
Russian Federation
Russian Federation
Kremlevskaya, 18, Kazan 420008
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Review
For citations:
Gubaev A.I., Rodionov A.A., Salakhov M.Kh., Subacheva I.N., Syrnikov P.P., Trepakov V.A., Yusupov R.V. Photoinduced EPR in KTa0.988Nb0.012O3 crystals. Magnetic Resonance in Solids. 2010;12(1):7-11.
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