Superconducting gap in Bi2Sr2CaCu2O8

Abstract

Reflectivity measurements, at different fixed frequencies, have been performed on ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_8$ films as a function of temperature and magnetic field. Analysis of the data provides evidence for an order parameter 2Δ(0)≃3.3${\mathit{k}}_{\mathit{B}}$ ${\mathit{T}}_{\mathit{c}}$ although the variation of this order parameter with temperature is significantly different from that predicted by the weak-coupling BCS model.