Raman-active phonons in Bi2Sr2-xLaxCuO6+d: Phonon assignment and charge-redistribution effects

Minoru Osada, Masato Kakihana, Mikael Käll, Lars Börjesson, Atsuyoshi Inoue, Masatomo Yashima

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Abstract

Phonon Raman spectra of Bi2Sr2-xLaxCuO6+d single crystals with x values close to 0, 0.4, and 0.8 have been investigated. Room-temperature measurements were performed in the five main polarization geometries, including the c-axis polarized configuration. We identify the 4A1g symmetry modes that are Raman allowed within the ideal body-centered-tetragonal unit cell, as well as several disorder activated phonon bands from the BiO and/or SrO layers. For an increasing degree of La doping, the O(2)Sr A1g mode at 624 cm-1 softens by 12 cm-1 between x=0 and x=0.8. We attribute this softening to a weakening of the Cu-O(2)Sr-Bi bond due to a reduction in Cu and Bi valences when going from the overdoped (x=0) to the underdoped (x=0.8) regime.

Original languageEnglish
Pages (from-to)2847-2851
Number of pages5
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume56
Issue number5
Publication statusPublished - 1997 Aug 1
Externally publishedYes

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ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Osada, M., Kakihana, M., Käll, M., Börjesson, L., Inoue, A., & Yashima, M. (1997). Raman-active phonons in Bi2Sr2-xLaxCuO6+d: Phonon assignment and charge-redistribution effects. Physical Review B - Condensed Matter and Materials Physics, 56(5), 2847-2851.