Spin dynamics in the metallic state of YBa2(Cu0.98Zn0.02)3O6+x

Inelastic neutron scattering measurements have been carried out on a YBa2(Cu0.98Zn0.02)3O6+x single crystal in both underdoped (x 0.7) and overdoped (x = 0.97) regimes. In the zinc substituted system, spin dynamics is drastically changed in respect to the pure compound: (i) the resonance peak almost vanishes, (ii) the spin gap is filled, (iii) new antiferromagnetic excitations are found at low energy. These new magnetic fluctuations, which persist in the normal state, account for a local enhancement of AF correlations around nonmagnetic impurities. Besides, it is worth emphasizing that features, not directly related to superconductivity, i.e., the contribution to the spin dynamics apart from the resonance peak and the spin pseudo-gap observed in the underdoped regime above Tc, coexist with the new low energy magnetic fluctuations