Signature of Carrier-Induced Ferromagnetism in Ti_{1-x}Co_{x}O_{2-delta}: Exchange Interaction Between High-Spin Co 2+ and the Ti 3d Conduction Band

摘要

X-ray photoemission spectroscopy measurements were performed on thin-filmsamples 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 stateand the shift due to the exchange splitting of the conduction band suggeststrong hybridization between carriers in the Ti 3d t2g band and the t2g statesof the high-spin Co 2+. These observations support the argument that roomtemperature ferromagnetism in Ti_{1-x}Co_{x}O_{2-delta} is intrinsic.