Electrical Resistivity and Thermoelectric Power of CuAu Alloy

The temperature dependences of the electrical resistivity and the thermoelectric power of CuAu alloy in the temperature range between 400° and 700°K are investigated on the basis of the theory recently developed by the authors to explain the origin of the long-period superlattice and the phase transitions in the CuAu alloy. The relaxation time of conduction electrons is determined by the scattering due to the lattice vibrations and the disorder arrangements of the Cu and Au atoms. The latter scattering mechanism is most important for explaining the temperature dependence of electrical resistivity. The energy gaps, which appear in CuAu I and CuAu II, modify the electron velocities in the vicinities of these gaps and cause the changes in the transport coefficients. It is found that the energy gaps in the $〈110〉$ directions are important for explaining the anomalous behavior of the phase dependences of the transport coefficients, especially that of the thermoelectric power.