Transport anomalies and the role of pseudogap in the 60-K phase of YBa2Cu3O7-δ

We report the result of our accurate measurements of the (a- and b-axis resistivity, Hall coefficient, and the a-axis thermopower in untwinned YBa2Cu3Oy single crystals in a wide range of doping. It is found that both the a-axis resistivity and the Hall conductivity show anomalous dependences on the oxygen content y in the 60-K phase below the pseudogap temperature T*. The complete data set enables us to narrow down the possible pictures of the 60-K phase, with which we discuss a peculiar role of the pseudogap in the charge transport.