Hole Localization And Superconductivity In La2cuo4+Delta

Hall coefficient of the oxygen-intercalated La214 cuprate was measured at room temperature and 77.4 K for delta = 0.015 - 0.110. The Hall number, defined as a quantity inversely proportional to the Hall coefficient. increased linearly with delta for delta < 0.030. However. for > 0.030. it was observed to be lower than the expected increase of hole carriers with increasing d This indicated the existence of localized holes in the electronically phase separated superconducting phases. Our resistivity and the thermopower measurements were also consistent with this conjecture.