Extended paraconductivity regime in underdoped cuprates

Abstract

We reconsider transport experiments in strongly anisotropic superconducting cuprates and we find that universal Aslamazov-Larkin (AL) paraconductivity in two dimensions is surprisingly robust even in the underdoped regime below the pseudogap crossover temperature T^*. We also establish that the underlying normal state resistivity in the pseudogap phase is (almost) linear in temperature, with all the deviations being quantitatively accounted by AL paraconductivity. The disappearence of paraconductivity is governed by the disappearence of gaussian pair fluctuations at an energy scale related to T^*.