THERMOELECTRIC VOLTAGE AT METALLIC POINT CONTACTS FROM NONEQUILIBRIUMEFFECTS

This paper presents results for thermoelectric voltage experiments car ried out with metallic point contacts. The motivation for this work is the fundamental understanding of the nonequilibrium state between ele ctrons and phonons, and for applying this phenomenon to a point temper ature measurement of small heating elements like an LSI (Large-Scale I ntegration) electronic chip. The experiments were carried out by using gold, silver, copper, and tungsten point contacts under cryogenic con ditions, and a heat flux through the point contact was applied via a t emperature difference across the contact. In this condition, thermoele ctric voltages appeared even when the entire open circuit consisted of only one material. This phenomenon was explained theoretically by con sidering the nonequilibrium effect between the phonon and electron tem peratures, and the geometric effect at the point contact. Good agreeme nt was found between the theory and the experiment.