Resonance mode in B1g Raman scattering:: A way to distinguish between spin-fluctuation and phonon-mediated d-wave superconductivity

We argue that Raman scattering in B-1g symmetry allows one to distinguish between phonon-mediated and magnetically mediated d-wave superconductivity. In spin-mediated superconductors, B-1g Raman intensity develops a resonance at a frequency Omega(res)< 2 Delta(max), whose origin is similar to a neutron resonance. In phonon-mediated d-wave superconductors, such a resonance does not develop. Several extensions of the argument are presented.