Anomalous pseudogap and superconducting-state properties of heavily disordered Y1−xCaxBa2(Cu1−yZny)3O7−δ

Abstract

The role of substantial in-plane disorder (Zn) on the charge transport and ac susceptibility of Y1−xCaxBa2(Cu1−yZny)3O7−δ was investigated over a wide range of planar hole concentration p. Resistivity ρ(T) for a number of overdoped to underdoped samples with y⩾0.055 showed clear downturns at a characteristic temperature similar to that found at T* in Zn-free underdoped samples because of the presence of the pseudogap. Contrary to the widely observed behavior for underdoped cuprates at lower Zn contents (where the pseudogap energy increases almost linearly with decreasing p in the same way as for the Zn-free compounds), this apparent pseudogap temperature at high Zn content showed very little or no p dependence. It also increases systematically with increasing Zn concentration in the CuO2 planes. This anomalous behavior appears quite abruptly, e.g., samples with y⩽0.05 exhibit the usual T*(p) behavior. AC susceptibility of these heavily disordered samples showed the superfluid density to be extremely low. We also discuss various possible scenarios that might lead to an anomalous Zn-induced pseudogap in the cuprates.

Source-reported materials — not catalogue approval

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