Evidence for two distinct energy scales in the Raman spectra of YBa2(Cu1-xNix)3O6.95 -: art. no. 177401

We report electronic Raman scattering from Ni-substituted YBa2Cu O-3(6.95) single crystals with T-c ranging from 92.5 to 78 K. The fully symmetrical A(1g) channel and the B-1g channel which is sensitive to the d(x)(2)-y(2) gap maximum have been explored. The energy of the B-1g pair-breaking peak remains constant under Ni doping while the energy of the A(1g) peak scales with T-c (E-A1g/k(B)T(c) = 5 ). Our data show that the A(1g) peak tracks the magnetic resonance peak observed in inelastic neutron scattering yielding a key explanation to the long-standing problem of the origin of the A(1g) peak.