Pairing symmetry and localization probed by electronic Raman scattering in disordered high-Tc superconductors

The study of electronic Raman spectra of deliberately disordered Bi2Sr2Ca(Cu1-xFex)(2)O-delta crystals has revealed that static (omega-->0) limits of the ratio between the Raman susceptibilities from the superconducting and normal state show the universality expected for the gap with nodes. In addition, the B-1g channel, where the static Limits are slightly varied by the disorder, also demonstrates independence of impurity concentration for low-frequency Raman susceptibility, signaling that the nodes are shifted from the positions predicted by a pured symmetry. [S0163-1829(99)03326-3].