  We investigate the origin of charge density wave (CDW) formation in
insulators by studying BaIrO3 using high resolution (1.4 meV) photoemission
spectroscopy. The spectra reveal the existence of localized density of states
at the Fermi level in the vicinity of room temperature. These localized states
are found to vanish as the temperature is lowered thereby, opening a soft gap
at the Fermi level, as a consequence of CDW transition. In addition, the energy
dependence of the spectral density of states reveals the importance of magnetic
interactions, rather than well-known Coulomb repulsion effect, in determining
the electronic structure thereby implying a close relationship between
ferromagnetism and CDW observed in this compound. Also, Ba core level spectra
surprisingly exhibit an unusual behavior prior to CDW transition.
