Abstract
We study the surface and bulk electronic structure of the room-temperature ferromagnet anatase films using soft- and hard-x-ray photoemission spectroscopy with probe sensitivities of and , respectively. We obtain direct evidence of metallic states in the bulk, which get suppressed to give a surface semiconductor, thus indicating the difference in electronic structure between surface and bulk. X-ray absorption and resonant photoemission spectroscopy reveal electrons at the Fermi level () and high-spin electrons occurring away from . The results show the importance of the charge neutrality condition: ( is oxygen vacancy), which gives rise to the elusive Ti carriers mediating ferromagnetism via the Co exchange interaction pathway of the occupied orbitals.
- Received 11 August 2010
DOI:https://doi.org/10.1103/PhysRevLett.106.047602
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