Raman-active phonons in Phonon assignment and charge-redistribution effects

Minoru Osada, Masato Kakihana, Mikael Käll, Lars Börjesson

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

Phonon Raman spectra of (Formula presented) single crystals with (Formula presented) 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 (Formula presented)-axis polarized configuration. We identify the (Formula presented) 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 (Formula presented) mode at (Formula presented) softens by (Formula presented) between (Formula presented) and (Formula presented) We attribute this softening to a weakening of the (Formula presented) bond due to a reduction in Cu and Bi valences when going from the overdoped (Formula presented) to the underdoped (Formula presented) regime.

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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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