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Raman spectroscopy with UV excitation on untwinned single crystals of YBa 2 Cu 3 O 7– δ
Author(s) -
Bahrs S.,
Reich S.,
Zwick A.,
Goñi A. R.,
Bacsa W.,
Nieva G.,
Thomsen C.
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200409061
Subject(s) - raman spectroscopy , photobleaching , excitation , anisotropy , materials science , dielectric , analytical chemistry (journal) , nuclear magnetic resonance , chemistry , molecular physics , optics , optoelectronics , fluorescence , physics , chromatography , quantum mechanics
Recent reflectance anisotropy studies on the material showed a photobleaching effect in the in‐plane components of the dielectric function around 2.2 and 4.1 eV [1]. We present Raman spectra of oxygen deficient YBa 2 Cu 3 O 7– δ detwinned single crystals taken with laser excitation of 3.7 eV, close to the UV feature in the dielectric function, in search for a signal from the defect‐induced Raman modes. While two groups of defect‐induced mode at 230 cm –1 and 600 cm –1 behave very similar at the 2.2 eV resonance, we find clear differences for UV excitation. A peak at 600 cm –1 is identified as a copper‐oxygen‐chain related, defect‐induced modes by its Raman selection rules. While this mode is enhanced beyond the strength of the Raman‐allowed modes, the group at 230 cm –1 is absent. Low temperature experiments showed no change of the peak height under illumination, though the peaks are known to photobleach in the visible. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)