Paramagnetic Excited State of FeSi

Abstract

The anomalous behavior of the temperature dependence of the susceptibility and specific heat of the intermetallic compound FeSi is reexamined from both an experimental and a theoretical point of view. It is shown that a consistent set of experimental data is obtained below a temperature of about 700°K. An interpretation of the thermodynamic properties is given, based on a model that requires the existence of correlated magnetic excited states only a few hundred degrees above the nonmagnetic ground state. Other, more conventional models are also explored, and the reasons for their rejection are discussed.