摘要
We have studied magnetism in Ti 1 - x Co x O 2 - δ thin films with various x and δ by soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L 2, 3 absorption edges. The estimated ferromagnetic moment by XMCD was 0.15-0.24μ B /Co at the surface, while in the bulk it was 0.82-2.25μ B /Co, which is in the same range as the saturation magnetization of 1.0-1.5μ B /Co. These results suggest an intrinsic origin of the ferromagnetism. The smaller moment of the Co atom at the surface is an indication of a magnetically dead layer of a few nanometers thick at the surface of the thin films. © 2011 IOP Publishing Ltd.