Electronic structure of semimetals from transport and fermiology experiments

For at least thirty years most of the generic features desirable in a material to have potential for a high thermoelectric figure of merit have been known and generally not disputed. Most of these involve some aspect of the electronic structure. The latter can be measured or at least qualitatively evaluated using traditional transport and fermiology experiments. These include temperature dependent electrical resistivity, low and high field Hall effect and magnetoresistance, and the Shubnikov-de Haas (or equivalently de Haas-van Alphen) effect. In this paper the theoretical basis for this kind of an evaluation will be given, with emphasis on the semimetallic class of materials where most thermoelectrics are found but which present their own problems. The four experimental techniques mentioned above will be described and some of the subtleties of the data reduction and analysis illustrated.