Role of Ti 3d Carriers in Mediating the Ferromagnetism of CoTiO2 Anatase Thin Films

T. Ohtsuki, A. Chainani, R. Eguchi, M. Matsunami, Y. Takata, M. Taguchi, Y. Nishino, K. Tamasaku, M. Yabashi, T. Ishikawa, M. Oura, Y. Senba, H. Ohashi, and S. Shin
Phys. Rev. Lett. 106, 047602 – Published 25 January 2011
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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 3dO 2pTi 3d exchange interaction pathway of the occupied orbitals.

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  • Received 11 August 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.047602

© 2011 American Physical Society

Authors & Affiliations

T. Ohtsuki1, A. Chainani1, R. Eguchi1,2, M. Matsunami1,2, Y. Takata1, M. Taguchi1, Y. Nishino1, K. Tamasaku1, M. Yabashi3, T. Ishikawa1, M. Oura1, Y. Senba3, H. Ohashi3, and S. Shin1,2

  • 1RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
  • 2Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
  • 3JASRI/SPring-8, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan

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Issue

Vol. 106, Iss. 4 — 28 January 2011

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