Thermal transport in disordered systems

An exact result due to Chester and Thellung (1961) is extended to discuss thermal transport in disordered systems in general. The results are non-perturbative and are consequently true for arbitrary disorder. The authors conclude that, for low T, the thermal conductivity will scale as the electrical conductivity and thus the Wiedemann-Franz law is a very general result. In addition, they find weak localisation corrections to the thermopower will be present. The nature of fluctuations in the thermal transport coefficients are also discussed and compared with the phenomenon of universal conductance fluctuations.