Raman-active phonons in Bi{sub 2}Sr{sub 2{minus}x}La{sub x}CuO{sub 6+d}: Phonon assignment and charge-redistribution effects

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.56.2847· OSTI ID:528089

Osada, M; Kakihana, M ^[1]; Kaell, M; Boerjesson, L ^[2]; Inoue, A; Yashima, M ^[1]

---

1. Materials and Structures Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226 (Japan)
2. Department of Applied Physics, Chalmers University of Technology, S41296 Goeteborg (Sweden)

Phonon Raman spectra of Bi{sub 2}Sr{sub 2{minus}x}La{sub x}CuO{sub 6+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 4A{sub 1g} 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){sub Sr} A{sub 1g} mode at 624cm{sup {minus}1} softens by 12cm{sup {minus}1} between x=0 and x=0.8. We attribute this softening to a weakening of the Cu-O(2){sub 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. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 528089
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 5 Vol. 56; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BISMUTH OXIDES
CHARGE DISTRIBUTION
COPPER OXIDES
CRYSTAL DOPING
HIGH-TC SUPERCONDUCTORS
LANTHANUM OXIDES
PHONONS
RAMAN SPECTRA
STRONTIUM OXIDES
VACANCIES