We have measured the interlayer tunneling characteristics of slightly overdoped Bi2Sr2CaCu2O8+δ in the c-axis direction from 10 to 220 K by using very thin mesas containing approximately ten CuO2 double layers. The superconducting gap 2Δ is 50 meV at 10 K and shows a temperature (T) dependence similar to that of the BCS theory. A pseudogap evolves below 150 K, where the c-axis resistivity ρc is semiconducting. The normal-state tunneling resistance RN shows a linear T dependence down to Tcexhibits an abrupt decrease at Tcand saturates at low T. This reflects scattering arising from an electronic interaction that is relevant to the high- Tc superconductivity.
ASJC Scopus subject areas