Transport Properties of YBa ₂ Cu ₃ O ₇ : Resistivity, Thermal Conductivity, Thermopower and Hall Effect

Abstract

For the high-Tc superconductor YBa2Cu3O7, we present results on the resistivity, Hall effect, and thermopower for temperatures up to 350 K as well as on the thermal conductivity in the range 0.2 K ⩽ T ⩽ 120 K. The Hall coefficient is positive and varies approximately with T-1. The thermopower is very small and sample dependent. These results suggest transport in more than one band. The thermal conductivity indicates dominant phonon heat transport. For the residual resistivity an upper bound, ρ0 ⩽ 250 μΩ cm, is deduced. Combining this with published results for the slope of the upper critical field and the penetration depth, we estimate the specific-heat coefficient, 5 ⩽ γ < 9 mJ/K2 mole-Cu, and the effective carrier density, 1.1 · 1022 cm-3.