Temperature and substitution dependence of the photoemission spectra of FeSi

We have studied the effect of varying temperature and Co substitution on the low-energy electronic structure of FeSi by photoemission spectroscopy. We have observed that the density of states (DOS) of FeSi is reduced at low temperatures over a wide energy range of (Formula presented) below the Fermi level (Formula presented) which is the energy scale observed by the magnetic, transport and optical measurements. The reduced DOS is completely recovered with increasing temperature but only partly, i.e., predominantly near (Formula presented) with Co substitution, again consistent with the transport properties.