ELIASHBERG FUNCTION OF CUPRATES AND FULLERIDES FROM GAP MEASUREMENTS

Assuming s-wave boson-exchange electronic-pairing superconductivity, we obtain indications on the electron-boson coupling spectral function of cuprates and fullerides from the experimental gap measurements. In cuprates, the coupling is quite strong and it is concentrated in a region of frequencies of the order of 2550 meV. From a careful analysis of the incompatibility of the infrared and the other gap measures on these materials, we obtain evidence for the validity of our framework. If the large gap values reported by tunneling on fullerides are confirmed then at least 90% of the coupling in these materials is concentrated in a low-energy region at 10 meV, the rest being concentrated in a high-energy region 180200 meV. © 1994 The American Physical Society.