Spin fluctuations and properties of the thermoelectric power of nearly ferromagnetic iron monosilicide

The thermoelectric power of nearly ferromagnetic iron monosilicide, which p asses through an electronic semiconductor-metal transition with increasing temperature, is investigated theoretically. The results of this investigati on indicate that a sizable paramagnon-related increase in charge carriers c an occur in nearly ferromagnetic semiconductors, and that spin fluctuations can modify the electronic spectrum and thereby renormalize the diffusion c omponent of the thermoelectric power. The transition from semiconductor to metal decreases the paramagnon component sharply and the thermoelectric pow er changes sign, which agrees with experimental data for iron monosilicide. (C) 1999 American Institute of Physics. [S1063-7834(99)02706-9].