鉛系酸化物高温超伝導体のラマン散乱

抄録

The Raman spectra of (Pb₂Cu)Sr₂Y_1-xCa_xCu₂O_8+δ (Pb3212), (Pb₂Cu)Sr_0.9La_1.1CuO_6+δ (Pb3201), and (Pb_0.5Cu_0.5)Sr₂YCu₂O_7+δ (Pb1212) were studied and vibrational assignments in harmony with the layer stacking sequencies found in these Pb-based high-Tc superconducting oxides were proposed. In particular, the assignment of the 480-and 580-cm^-1 Raman bands to oxygen in the PbO and SrO layers, respectively, was unambiguously established. In the case of Pb3212 we found that the intensities of modes connected to the CuO₂-plane vibrations decreased with increasing carrier concentration. This effect was attributed to the increased metallic screening in the CuO₂ planes that can be expected in the hole-rich Ca-doped samples.