Odd and even magnetic resonant modes in highly overdoped Bi2Sr2CaCu2O8+δ

We present inelastic neutron scattering data on highly overdoped Bi2Sr2CaCu2O8+delta single crystals with superconducting transition temperature T-C=70 K and, for comparison, a nearly optimally doped crystal with T-C=87 K. In both samples, magnetic resonant modes with odd and even symmetry under exchange of the two CuO2 layers in the unit cell are observed. In the overdoped sample, the linewidth of the odd mode is reduced compared with the optimally doped sample. This finding is discussed in conjunction with recent evidence for intrinsic inhomogeneities in this compound. The data on odd and even resonant excitations are otherwise fully consistent with trends established on the basis of data on YBa2Cu3O6+x. This confirms the universality of these findings and extends them into the highly overdoped regime of the phase diagram.