Magnetic resonant excitations in high-Tc superconductors

The observation of an unusual spin resonant excitation in the superconducting state of various High-T-c copper oxides by inelastic neutron scattering measurements is reviewed. This magnetic mode is discussed in light of a few theoretical models and likely corresponds to a spin-1 collective mode. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.