1206.0339 (V. R. Singh et al.)

Ferromagnetism of cobalt-doped anatase TiO$_2$ studied by bulk- and
surface-sensitive soft x-ray magnetic circular dichroism    [PDF]

V. R. Singh, K. Ishigami, V. K. Verma, G. Shibata, Y. Yamazaki, T. Kataoka, A. Fujimori, F. -H. Chang, D. -J. Huang, H. -J. Lin, C. T. Chen, Y. Yamada, T. Fukumura, M. Kawasaki

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.

View original: http://arxiv.org/abs/1206.0339