Magnetic resonance at 41meV and charge dynamics in YBa2Cu3O6.95

– We report an Eliashberg analysis of the electron dynamics in YBa2Cu3O6.95. The magnetic resonance at 41 meV couples to charge carriers and defines the characteristic shape in energy of the scattering rate τ−1(T, ω), which allows us to construct the charge-spin spectral density Iχ(ω, T ) at temperature T . The T -dependence of the weight under the resonance peak in Iχ(ω) agrees with experiment as does that of the London penetration depth and of the microwave conductivity. Also, the T = 0 condensation energy, the fractional oscillator strength in the condensate, and the ratio of gap-to-critical temperature agree well with the data. A hallmark of the spin dynamics of several classes of high-Tc superconductors is a magnetic resonance observed around 40meV by means of spin-polarized inelastic neutron scattering. The position in energy of the peak scales with the critical temperature both in YBa2Cu3O6.95 (Y123) and Bi2Sr2CaCu2O8 (Bi2212) superconductors [1]. The analysis of the optical conductivity shows that the charge carriers are strongly coupled to the magnetic excitations with a coupling strength sufficient to account for superconducting transition temperatures 90K [2]. Thus, neutron scattering data combined with optical conductivity results, signal the prominence of the resonance mode for superconductivity in the cuprates. The analysis of additional optical data by Schachinger and Carbotte [3] showed that similar magnetic resonances are expected to be found in many other high-Tc materials with Tc 90K and that this phenomenon is not restricted to bilayer materials. At the moment some of these cannot be investigated with neutrons due to minuscule crystal size. Because the spectral weight under the resonance is maximized at T Tc and vanishes at T Tc [4] (at least in optimally doped Bi2212 and Y123), coupling of the conducting carriers to the magnetic mode ought to influence the temperature dependence of a variety of