Magnetic Resonant excitations in High-{$\rm T_c$} superconductors
  The observation of an unusual spin resonant excitation in the superconducting state of various High-Tc ~copper oxides by inelastic neutron scattering measurements is reviewed. This magnetic mode % (that does not exist in conventional superconductors) is discussed in light of a few theoretical models and likely corresponds to a spin-1 collective mode. 
Y. Sidis, S. Pailh\`es, B. Keimer, P. Bourges, C. Ulrich, L.P.   Regnault