Temperature dependence of the Raman scattering in HgBa2Cu4+delta

The temperature dependence of the high frequency Raman mode in HgBa2CuO4+de lta belonging to the vibrations of the apical oxygen has been studied in th e temperature range of 300-10 K in samples with different values of delta. The frequency, linewidth, and lineshape of this mode are found to exhibit a non-monotonic variation with temperature. The trends in the temperature de pendent variation are found to be qualitatively the same in over-. under-, and optimally oxygen doped samples, although there are quantitative sample dependent differences, We show that the maximum change in the frequency and the asymmetry of this peak are linear in the excess oxygen content, delta. (C) 2001 Published by Elsevier Science Ltd.