General expressions for the electrical resistivity and thermal conductivity of twinned crystals

Abstract

General expressions are derived for the electrical resisitivity and thermal conductivity of a twinned single crystal. Particular attention is paid to the effect of the structure of the twin domains on these transport coefficients. Edge effects are also considered. The expression for the thermal conductivity is used to fit data for a twinned single crystal of 0.8% Zn-doped YBa2Cu3O6.98. The expression for the electrical resistivity is used to fit previously published electrical resistivity data for a twinned single crystal of YBa2Cu3O6.9. It is found that twin boundaries are not a significant source of electron scattering in high-quality single crystals of Y-123. We cannot rule out scattering of phonons by twin boundaries in these crystals, with up to 12% suppression of the phonon component of the thermal conductivity. The related problem of determining the electrical resistivity and thermal conductivity of a crystal with oblique and alternating isotropic regions of different conductivities is also solved.