Magnetic resonance peak and nonmagnetic impurities
  Nonmagnetic Zn impurities are known to strongly suppress superconductivity. We review their effects on the spin excitation spectrum in $\rm YBa_2Cu_3O_{7}$, as investigated by inelastic neutron scattering measurements. 
Y. Sidis, P. Bourges, B. Keimer, L. P. Regnault, J. Bossy, A. Ivanov,   B.Hennion, P. Gautier-Picard, G.Collin