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Optical phonons in superconducting Sm 1.85Ce 0.15CuO 4 single crystals

Title
Optical phonons in superconducting Sm 1.85Ce 0.15CuO 4 single crystals
Authors
Choi E.-M.Mun M.-O.Yang I.-S.Kim Y.J.Kim J.H.Park S.R.Kim W.T.Rha S.H.Beom-hoan O.
Ewha Authors
양인상
SCOPUS Author ID
양인상scopus
Issue Date
1999
Journal Title
Journal of the Korean Physical Society
ISSN
0374-4884JCR Link
Citation
vol. 34, no. 3, pp. 292 - 296
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
We report Raman and infrared measurements of optical phonons in superconducting Sm 1.85Ce 0.15CuO 4 single crystals (T c = 15 K). All zone-center phonon modes predicted by a factor-group analysis have been identified, except for the low-frequency E g mode involving Sm(Ce) atoms. Two additional c-axis modes with A 1g symmetry were found at 134 cm -1 and 591 cm -1 in the Ramari spectra. We identify the 134 cm -1 mode as the lowest-frequency infrared-active c-axis A 2u mode, mixed into the Raman spectra due to disorder via a breakdown of the usual exclusive selection rule. The 591 cm -1 Raman mode is found to be closely connected with an extra infrared mode observed at the same frequency. Our measurements on Sm 2-xCe xCuO 4 (x = 0.0 - 0.18) ceramics show, for the first time, that the strong Raman peak at 591 cm -1 appears only in the narrow range of Ce-doping, 0.1 ≤ x ≤ 0.17, which nearly coincides with the Ce-doping range where the Sm 2-xCe xCuO 4 system is superconducting at low temperatures.
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자연과학대학 > 물리학전공 > Journal papers
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