Phonon Raman scattering ofNbBa2Cu3OyandNd1.6Ba1.4Cu3Oy

Polarized Raman scattering from ${\mathrm{NdBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{\mathit{y}}$ and ${\mathrm{Nd}}_{1.6}$ ${\mathrm{Ba}}_{1.4}$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{\mathit{y}}$ single crystals is reported. Single-phonon peaks have been observed in ${\mathrm{NdBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{\mathit{y}}$ at 136, 168, 316, 448, 508, and 580 ${\mathrm{cm}}^{\mathrm{-}1}$ at room temperature where the 316- and 580-${\mathrm{cm}}^{\mathrm{-}1}$ peaks are strong in the (x,x) while the 448- and 508-${\mathrm{cm}}^{\mathrm{-}1}$ peaks are strong in the (z,z) configurations. The 316-${\mathrm{cm}}^{\mathrm{-}1}$ peak is found to separate into two peaks at 290 and 323 ${\mathrm{cm}}^{\mathrm{-}1}$ at 4 K, which are assigned as in-phase and out-of-phase vibration of oxygen atoms in the Cu-O plane, respectively. The polarization dependence of the scattering peaks has been explained on the basis of the characteristics of the electronic transitions. The energy shift of peaks when Ba is substituted by Nd has also been discussed.