RESISTIVITY OF HIGH-TC SUPERCONDUCTORS - LINEAR IN T AT CONSTANT-P, NONLINEAR AT CONSTANT-V

The observed constant-pressure resistivity ρ{variant}p of most high-Tc superconductors is linear in temperature T over large ranges. We show that this is not true for the constant-volume resistivity ρ{variant}v; for 1-2-3 YBCO the correction from ρ{variant}p to ρ{variant}v is -32% at 500 K relative to the low-T value. Since theory predicts ρ{variant}v rather than ρ{variant}p, the observed linearity of ρ{variant} probably cannot be used as a tool to choose between theories for high-Tc superconductivity. © 1990.