c-axis transport and phenomenology of the pseudogap state in Bi2Sr2CaCu2O(8+delta)

We measure and analyze the resistivity of Bi2Sr 2CaCu2O8+? crystals for different doping ?. We obtain the fraction of carriers ?(T, ?)=n g/ntot that do not participate in the c-axis conductivity. All the curves ?(T, ?) collapse onto a universal curve when plotted against a reduced temperature x=[T-?(?)]/?*(?). We find that at the superconducting transition ng is doping independent. We also show that a magnetic field up to 14 T does not affect the degree of localization in the (a, b) planes but widens the temperature range of the x scaling by suppressing the superconducting phase coherence.