Dynamic spin-response function of the high-temperature Bi2Sr2CaCu2O8+δ superconductor from angle-resolved photoemission spectra

We introduce a formalism for calculating dynamic response functions using experimental single-particle Green's functions. As an illustration of this procedure, we estimate the dynamic spin-response of the cuprate superconductor Bi2Sr2CaCu2O8+delta. We find good agreement with superconducting state neutron data, in particular, the (pi,pi) resonance with its unusual hourglass shaped dispersion. We anticipate that our formalism will also be useful in interpreting results from other spectroscopies, such as optical and Raman responses.