SUPERCONDUCTIVITY INDUCED PHONON ANOMALIES IN THE RAMAN-SPECTRA OF ZNAND NI DOPED YBA2CU3O7

Here we present Raman spectra of YBa2(Cu1-xZnx)3O7 and YBa2(Cu1-xNix)3 O7 as a function of temperature and Zn or Ni content. The temperature dependence of two modes at 340 and 440 cm-1 is analyzed. Similarly to the infrared measurements it is found that Zn substantially suppresses the superconductivity induced phonon softening whereas, Ni does not a ffect much that effect. Moreover, the superconductivity induced phonon stiffening of the 440 cm-1 mode completely disappeared with the Zn do ping. We find this behaviour might support the model where Zn acts eff ectively as a magnetic pair breaker.