Out-of-plane conductivity in single-crystal YBa2Cu3O7

Abstract

The resistivity anisotropy has been measured in seven single crystals of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$. We find that the anisotropy is between 56 and 110 at 290 K, increasing to ∼250 just above $T_c$ (90–93 K). While the out-of-plane resistivity ${\rho }_c$ is close to the Mott limit, the large in-plane resistivity ${\rho }_{\mathrm{ab}}$ (120–150 μΩ cm at 290 K) implies a large metallic parameter ($k_F$l∼31) and long electronic mean free path (67 Å at 100 K). Both ${\rho }_c$ and ${\rho }_{\mathrm{ab}}$ are well described by the equation ρ=A/T+BT recently proposed by Anderson and Zou.