BAND-STRUCTURE AND SEMICONDUCTING PROPERTIES OF FESI

The results of linear augmented-plane-wave band calculations for cubic FeSi, carried out in the local-density approximation, predict a small (approximately 0.11 eV) indirect semiconductor gap which agrees well with empirical estimates (approximately 0.13 eV). The origin of this g ap, which occurs within the Fe (3d) manifold, can be traced to a pseud ogap that is present in the reference rocksalt phase that underlies th e lower-symmetry FeSi structure. The relationship between the FeSi ban d structure and several types of many-body correlation mechanisms that have been advanced to explain its anomalous temperature-dependent mag netic properties is discussed.