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Raman study of pure and doped (Li,Sr) single crystals of La/sub 2/CuO/sub 4-//sub y/

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)
Raman spectra are presented of pristine and doped (Sr,Li) single crystals of La/sub 2/CuO/sub 4-//sub y/. Based on polarization measurements, we assign the 424-cm/sup -1/ line to the symmetric A/sub 1//sub g/ vibration of the out-of-plane oxygen atoms along the tetragonal axis. The line at 231 cm/sup -1/ is identified as the A/sub 1//sub g/ vibration of the La atoms along the tetragonal axis and the line at 238 cm/sup -1/ as the E/sub g/ vibration of the out-of-plane oxygen atoms parallel to the Cu-O layers. A symmetry-forbidden Raman line is observed at 680 cm/sup -1/ which, by comparison with infrared measurements, can be tentatively assigned to an in-plane oxygen vibration. The dependence of the Raman spectra upon Li and Sr doping is presented and discussed. Especially noteworthy are two strong and sharp Raman lines (at 757 and 773 cm/sup -1/ at room temperature) in the Sr-doped crystals, because of their higher frequencies, polarization sensitivities, and unusual temperature dependences.
Research Organization:
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
OSTI ID:
6757560
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 39:4; ISSN PRBMD
Country of Publication:
United States
Language:
English