%0 Journal Article
%T Ferromagnetism of cobalt-doped anatase TiO$_2$ studied by bulk- and surface-sensitive soft x-ray magnetic circular dichroism
%A V. R. Singh
%A K. Ishigami
%A V. K. Verma
%A G. Shibata
%A Y. Yamazaki
%A T. Kataoka
%A A. Fujimori
%A F. -H. Chang
%A D. -J. Huang
%A H. -J. Lin
%A C. T. Chen
%A Y. Yamada
%A T. Fukumura
%A M. Kawasaki
%J Physics
%D 2012
%I arXiv
%R 10.1063/1.4729123
%X We have studied magnetism in anatase Ti$_{1-x}$Co$_x$O$_{2-\delta}$ ({\it x} = 0.05) thin films with various electron carrier densities, by soft x-ray magnetic circular dichroism (XMCD) measurements at the Co $L_{2,3}$ absorption edges. For electrically conducting samples, the magnetic moment estimated by XMCD was $<$ 0.3 $\mu_B$/Co using the surface-sensitive total electron yield (TEY) mode, while it was 0.3-2.4 $\mu_B$/Co using the bulk-sensitive total fluorescence yield (TFY) mode. The latter value is in the same range as the saturation magnetization 0.6-2.1 $\mu_B$/Co deduced by SQUID measurement. The magnetization and the XMCD intensity increased with carrier density, consistent with the carrier-induced origin of the ferromagnetism.
%U http://arxiv.org/abs/1206.0339v1