Interlayer charge transport in the pseudogap state

Previously I have posted about the unusual anisotropies present in the temperature dependence of the resistivity in the pseudogap phase of the cuprates. In particular, the intralayer resistivity exhibits a metallic temperature dependence whereas the the interlayer resistivity exhibits a semi-conductor like temperature dependence. Much had been made of this previously with exotic explanations in terms of spin-charge separation. However, I posted about recent work showing how the data has a natural explanation in terms of the presence of a pseudogap with nodes in the same direction as that at which the interlayer hopping vanishes.
[This interlayer hopping anisotropy is quite important in understanding Angle-Dependent-MagnetoResistance (ADMR)].

I recently became aware of earlier phenomenological work by Tao Xiang and collaborators which also gives this explanation. In particular, this PRB gives a nice "universal" phenomenological form for the temperature dependence of the interlayer conductivity. This form is compared to data from a wide range of cuprates.