Thermoelectric Power of Insulators and Reconsideration of Kelvin's Relations at Low Temperatures

Abstract

Thermoelectric effects in Kondo insulators are attracting interests because of the emerging possibility of developping better thermoelectric materials for a portable refrigerator without liquid coolant. In this article, the theory of thermoelectric effects are reinvestigated for insulators or semiconductors at low temperatures. It is found that the famous relations established by Lord Kelvin for metals in 1851 must be modified for insulators in order to be consistent with the third law of the thermodynamics. Effects of strong correlation are discussed.