Phonon screening in high-temperature superconductors
In good conductors optical phonons are usually screened, and therefore not observed. However, sharp features due to infrared-active modes in the copper-oxygen planes are observed in the optical conductivity of Pr1.85Ce0.15CuO4 and YBa2Cu3O6.95. Oscillator strengths indicate that the screening of these modes is poor or totally absent. These materials are compared with eta-Mo4O11, in which lattice modes appear suddenly below the charge-density wave transition. It is proposed that poor screening in the cuprates originates from fluctuating charge inhomogeneities in the copper-oxygen planes.
Homes
CC
Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA.
McConnell
AW
Clayman
BP
Bonn
DA
Liang
R
Hardy
WN
Inoue
M
Negishi
H
Fournier
P
Greene
RL