Abstract
Dilute magnetic semiconductors (DMS) are materials in which a semiconductor is doped with a small amount of transition-metal atoms to induce magnetic properties necessary for spintronics and no deteriorate the optical and electronic properties. Recent research works indicate that the magnetic properties concerned with the electronic structure and the nanoscale effect are interesting and important. We used soft X-ray absorption to probe the electronic structure and the nanoscale effect of material-CeO2(Co). Soft X-ray absorption (XAS) is a powerful tool for studying DMS. In this thesis, we studied XAS of CeO2(Co) with the X-ray energy tuned about Co L-edge,O K-edge, and Ce M-edge. The Co2+ ions doped in CeO2 exhibit a high spin state. Our XAS results indicate that the Coulomb interaction of Co core holes and electrons increases with the increase of concentration of Co. The hybridization between Ce and O will be enhanced as the particle size is in the nano scale regime. We also found that the Ce3+ and Ce4+ coexist in CeO2(Co) and the formation of Ce3+ is suppressed by increase of Co concentration.