Role of Ti 3d carriers in mediating the ferromagnetism of Co∶TiO2 anatase thin films.
Role of Ti 3d carriers in mediating the ferromagnetism of Co∶TiO2 anatase thin films.
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DOI：
10.1103/physrevlett.106.047602
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发表时间：
2010-08
影响因子：
8.6
通讯作者：
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;S. Shin
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文献类型：
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作者：
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;S. Shin
利用探针灵敏度分别为~ 1和~ 10 nm的软x射线和硬x射线光电发射光谱研究了室温铁磁体Co∶TiO(2)锐钛矿薄膜的表面和体电子结构。我们获得了体中金属Ti（3+）态的直接证据，这些态被抑制得到表面半导体，从而表明了表面和体之间电子结构的差异。x射线吸收和共振光发射光谱显示Ti（3+）电子在费米能级（E(F)）和高自旋Co（2+）电子发生在E(F)之外。结果表明Co(2+)+V(O)(2-)+2Ti（4+）↔Co(2+)+2Ti(3+) （V(O)是氧空位）这一电荷中性条件的重要性，导致难以理解的Ti 3d载流子通过占据轨道的Co 3d-O 2p-Ti 3d交换相互作用途径介导铁磁性。
We study the surface and bulk electronic structure of the room-temperature ferromagnet Co∶TiO(2) anatase films using soft- and hard-x-ray photoemission spectroscopy with probe sensitivities of ∼1 and ∼10 nm, respectively. We obtain direct evidence of metallic Ti(3+) 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 Ti(3+) electrons at the Fermi level (E(F)) and high-spin Co(2+) electrons occurring away from E(F). The results show the importance of the charge neutrality condition: Co(2+)+V(O)(2-)+2Ti(4+)↔Co(2+)+2Ti(3+) (V(O) 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.