  X-ray photoemission spectroscopy measurements were performed on thin-film
samples of rutile Ti_{1-x}Co_{x}O_{2-delta} to reveal the electronic structure.
The Co 2p core level spectra indicate that the Co ions take the high-spin Co 2+
configuration, consistent with substitution on the Ti site. The high spin state
and the shift due to the exchange splitting of the conduction band suggest
strong hybridization between carriers in the Ti 3d t2g band and the t2g states
of the high-spin Co 2+. These observations support the argument that room
temperature ferromagnetism in Ti_{1-x}Co_{x}O_{2-delta} is intrinsic.
