Role of Ti 3d carriers in mediating the ferromagnetism of CoTiO2 anatase thin films

T. Ohtsuki, A. Chainani, Ritsuko Eguchi, M. Matsunami, Y. Takata, M. Taguchi, Y. Nishino, K. Tamasaku, M. Yabashi, T. Ishikawa, M. Oura, Y. Senba, H. Ohashi, S. Shin

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Abstract

We study the surface and bulk electronic structure of the room-temperature ferromagnet CoTiO2 anatase films using soft- and hard-x-ray photoemission spectroscopy with probe sensitivities of ∼1 and ∼10nm, respectively. We obtain direct evidence of metallic Ti3+ 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 Ti3+ electrons at the Fermi level (EF) and high-spin Co2+ electrons occurring away from EF. The results show the importance of the charge neutrality condition: Co2++VO2-+2Ti4+ Co2++2Ti3+ (VO is oxygen vacancy), which gives rise to the elusive Ti 3d carriers mediating ferromagnetism via the Co 3d-O 2p-Ti 3d exchange interaction pathway of the occupied orbitals.

Original languageEnglish
Article number047602
JournalPhysical Review Letters
Volume106
Issue number4
DOIs
Publication statusPublished - Jan 25 2011
Externally publishedYes

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Ohtsuki, T., Chainani, A., Eguchi, R., Matsunami, M., Takata, Y., Taguchi, M., Nishino, Y., Tamasaku, K., Yabashi, M., Ishikawa, T., Oura, M., Senba, Y., Ohashi, H., & Shin, S. (2011). Role of Ti 3d carriers in mediating the ferromagnetism of CoTiO2 anatase thin films. Physical Review Letters, 106(4), [047602]. https://doi.org/10.1103/PhysRevLett.106.047602