Griffin K A, Pakhomov A B, Wang C M, Heald S M, Krishnan Kannan M
Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.
Phys Rev Lett. 2005 Apr 22;94(15):157204. doi: 10.1103/PhysRevLett.94.157204.
Using complementary experiments we show that the room temperature ferromagnetism observed in anatase Co:TiO(2) films is not carrier mediated, but coexists with the dielectric state. TEM and x-ray absorption spectroscopy reveal a solid solution of Co in anatase, where Co is not metallic but in the +2 state substituting for Ti. Measurements at 300 K yield a M(S) of 1.1 mu(B)/Co atom, while all films are highly insulating. The evidence of intrinsic ferromagnetism in the dielectric ground state of Co:TiO(2) leads to new considerations for the origin of ferromagnetism in transition metal doped oxides.
通过互补实验，我们表明在锐钛矿型Co:TiO₂薄膜中观察到的室温铁磁性不是由载流子介导的，而是与介电态共存。透射电子显微镜（TEM）和X射线吸收光谱表明Co在锐钛矿中形成固溶体，其中Co不是金属态，而是以+2价替代Ti。在300K下的测量结果显示，每个Co原子的磁矩M(S)为1.1 μB，而所有薄膜都是高度绝缘的。Co:TiO₂介电基态中本征铁磁性的证据为过渡金属掺杂氧化物中铁磁性的起源带来了新的思考。
