Collective Spin Fluctuation Mode and Raman Scattering in Superconducting   Cuprates
  Although the low frequency electronic Raman response in the superconducting state of the cuprates can be largely understood in terms of a d-wave energy gap, a long standing problem has been an explanation for the spectra observed in the $A_{1g}$ polarization orientations. We present calculations which suggest that the peak position of the observed $A_{1g}$ spectra is due to a collective spin fluctuation mode. 
F. Venturini, U. Michelucci, T.P. Devereaux, A.P. Kampf