Conductivity of underdoped YBa2Cu3O7-δ:: Evidence for incoherent pair correlations in the pseudogap regime -: art. no. 197007

A two-channel scenario for the conductivity of underdoped YBa2Cu3O7-delta is proposed. One is the single-particle excitations channel, which dominates in the optimally doped material, whose resistivity is linear as a function of temperature. The other one gives a contribution which merges the 3D Aslamazov-Larkin fluctuation conductivity at low temperature and obeys a power law at high temperature, depending on two superconductive parameters (T-c and the zero temperature coherence length xi (c0)) and an energy scale Delta*. This allows one to address the nature of the pseudogap in favor of incoherent paining.