Is There a Unified Description of Conductivity of Layered Cuprates ?

AbstractWe present a novel approach to the analysis of the normal state in-plane $$\sigma _{ab} $$ and out-of-plane σcconductivities of anisotropic layered crystals such as oxygen deficient YBa2Cu3Ox. It can be shown that the resistive anisotropy is determined by the ratio of the phase coherence lengths in the respective directions; i.e., $$\sigma _{ab} /\sigma _c = \ell _{ab}^2 /\ell _c^2 $$ . From the idea that at all doping levels and temperatures T the out-of-plane transport in these crystals is incoherent, follows that $$\ell _c $$ is T-independent, equal to the spacing $$\ell _0 $$ between the neighboring bilayers. Thus, the T-dependence of $$\ell _{ab} $$ is given by the measured anisotropy, and $$\sigma _{ab} (\ell _{ab} )$$ dependence is obtained by plotting $$\sigma _{ab} {\text{ }}vs{\text{ }}\ell = {\text{ (}}\sigma _{ab} /\sigma _c )^{1/2} \ell _0 $$ .The analysis of several single crystals of YBa2Cu3Ox(6.35 < x < 6.93) shows that for all of them $$\sigma _{ab} (\ell ) $$ is described by a universal dependence $$\sigma _{ab} /\overline \sigma = f(\ell /\overline \ell ) $$ with doping dependent parameters $$\overline \sigma {\text{ }}and{\text{ }}\overline \ell $$ .