We study the electron thermal transport in granular metals at large tunnel
conductance between the grains, gT​≫1 and not too low a temperature T>gT​δ, where δ is the mean energy level spacing for a single grain.
Taking into account the electron-electron interaction effects we calculate the
thermal conductivity and show that the Wiedemann-Franz law is violated for
granular metals. We find that interaction effects suppress the thermal
conductivity less than the electrical conductivity.Comment: Replaced with published versio