Thermo-Coulomb effects in mesoscopic tunnel junctions

We present a study of the thermoelectric effect in tunnel junctions. In particular we calculate the thermopower coefficient S and the Peltier coefficient π. For macroscopic junctions we demonstrate the sensitivity of S and π to the structure of the density of states. For mesoscopic junctions we show that Coulomb effects modify the ordinary Onsager picture and the relation π=TS. The coefficients S and π are found to be very sensitive to the coupling of the junctions to the external world. We analyze measurements of the thermopower in granular films in terms of the thermo-Coulomb effects. We comment on the relevance of these effects to scanning tunneling microscope measurements.