Scaling behaviour of the c-axis resistivity in the pseudogap phase of high-temperature superconductors
Tao Xiang
Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100080, P.R. China
In the pseudogap phase of high-transition-temperature superconductors, the c-axis resistivity rc shows semiconductor-like temperature dependence, in contrast to the in-plane resistivity rab whose temperature dependence is metal-like. This dramatic difference between rc and rab is not what one might expect within the conventional Fermi liquid theory. The existing theoretical models based on the notion of dynamic confinement or incoherent interlayer hopping could not give a natural and unified explanation for experimental data. Here we show that the semiconducting behaviour of rc is in fact due to the interplay between the pseudogap and the anisotropic c-axis hopping integral. We argue that the pseudogap is the only energy scale governing the c-axis dynamics in the pseudogap phase of high-Tc cuprates and rc satisfies a single-parameter scaling law. We have derived an approximate expression for rc and found that it agrees well with the experimental data for Bi2Sr2CaCu2O8+d , Bi2Sr2Ca2Cu3O10+d, and YBa2Cu3O7-d. Our result suggests that the interlayer hopping is predominately coherent. The presence of a single energy scale puts a strong constraint on adequately theoretical description of high-Tc superconductivity.