Relationship among superconductivity, pseudogap, and high-energy   magnetic fluctuations in a model high-Tc superconductor from electronic Raman   scattering
  We use electronic Raman scattering to study the model single-layer cuprate superconductor HgBa2CuO4+d. In an overdoped sample, we observe a pronounced amplitude enhancement of a high-energy peak related to two-magnon excitations in insulating cuprates upon cooling below the critical temperature Tc. This effect is accompanied by the appearance of the superconducting gap and a pairing peak above the gap in the Raman spectrum, and it can be understood as a consequence of feedback of the Cooper pairing interaction on the high-energy magnetic fluctuations. All of these effects occur already above Tc in two underdoped samples, demonstrating a related feedback mechanism associated with the pseudogap. 
Yuan Li, M. Le Tacon, M. Bakr, D. Terrade, D. Manske, R. Hackl, L. Ji,   M. K. Chan, N. Barisic, X. Zhao, M. Greven and B. K...
cond-mat.supr-con cond-mat.str-el