Inelastic light scattering studies of overdoped Y1-xCaxBa2Cu3O7-delta thin film

Abstract

The vibrational and magnetic Raman excitation spectra were examined in overdoped Y1-xCaxBa2Cu3O7-delta thin films. Below T-c, certain phonons in undoped YBa2Cu3O7-delta (YBCO) show strong self-energy effects, which gradually vanish with increasing Ca concentration into the overdoped regime. The observed B-1g symmetry two-magnon excitation peak near 2900 cm(-1) in YBCO is significantly broadened, weakened, and shifts to the lower frequency with increasing Ca content, indicating the effective value of magnetic superexchange energy decreases and that the life time of the magrions becomes shorter with increasing hole concentrations. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.