c-axis transport and phenomenology of the pseudo-gap state in $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$

Abstract

We measure and analyze the resistivity of $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$ crystals for different doping $\delta$. We obtain the fraction of carrier $\eta (T,\delta )=n_g/n_{TOT}$ that do not participate to the c-axis conductivity. All the curves $\eta (T,\delta )$ collapse onto a universal curve when plotted against a reduced temperature $x=[T-\Theta (\delta )]/{\Delta }^{\ast }(\delta )$. We find that at the superconducting transition $n_g$ 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.

11 pages, 5 figures, submitted to Phys.Rev.B