We have measured the thermal conductivity, thermopower, Hall constant, and resistivity of a Y${\mathrm{Ba}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ high-$T_c$ superconductor. The thermal conductivity shows a striking increase below the transition temperature $T_c$, which we ascribe to an increase in lattice conduction due to a reduction in the scattering of phonons by holes as superconducting pairs form. This property, and the others we have measured, are consistent with ordinary metallic conduction mechanisms with short phonon and carrier free paths, and a strong interaction of phonons with a small density of hole carriers.

• Received 6 July 1987

DOI:https://doi.org/10.1103/PhysRevB.36.5680