NEUTRON AND RAMAN-SCATTERING STUDIES OF HGBA2CUO4+DELTA

The HgBa2CuO4+delta sample was characterized by Neutron diffraction an d magnetic measurements. Both of the measurements indicate a high puri ty of the sample. Raman measurement was performed on a HgBa2CuO4+delta compound of T-c = 96 K. The apical oxygen vibration at 592 cm(-1) was found to show (a) an above T-c anomaly, and (b) frequency hardening a nd linewidth broadening below the superconducting phase transition. Th e latter is attributed to the coupling of the phonon to the electronic excitation and related to the opening of the superconducting gap belo w the phonon frequency.