Moreau Relation and the Nernst Effect in Semiconductors

An empirical relation first proposed by Moreau and later by Bridgman expresses the Nernst coefficient of a metal as the product of the Thomson coefficient, electrical conductivity, and Hall coefficient. Thus a feature of this relation is that the Nernst coefficient changes sign whenever the slope of the Seebeck coefficient changes sign, behavior that has been observed to hold not only in metals but also in some semiconductors. Here, within the Boltzmann transport theory, we provide an evaluation of the extent to which the Moreau relation applies to semiconductor materials more generally, and specifically in the case of Bi₂Te₃. Implications for interpretation of Nernst measurements for determining charge carrier scatting mechanisms, as well as applications in thermomagnetic energy conversion, will also be discussed.