Department of Physics, University of Tokyo, Tokyo 113-0033, Japan.
J Phys Condens Matter. 2011 May 4;23(17):176002. doi: 10.1088/0953-8984/23/17/176002. Epub 2011 Apr 12.
We have performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies of the diluted ferromagnetic semiconductor Zn(1-x)Cr(x)Te doped with iodine (I) or nitrogen (N), corresponding to electron or hole doping, respectively. From the shape of the Cr 2p absorption peak in the XAS spectra, it was concluded that the Cr ions in the undoped, I-doped and lightly N-doped samples are divalent (Cr(2+)), while Cr(2+) and trivalent (Cr(3+)) coexist in the heavily N-doped sample. This result indicates that the doped nitrogen atoms act as acceptors but that doped holes are located on the Cr ions. In the magnetic field dependence of the XMCD signal at the Cr 2p absorption edge, ferromagnetic behaviors were observed in the undoped, I-doped, and lightly N-doped samples, while ferromagnetism was considerably suppressed in the heavily N-doped sample, which is consistent with the results of magnetization measurements.
我们对掺碘（I）或氮（N）的稀释铁磁半导体 Zn(1-x)Cr(x)Te 进行了 X 射线吸收光谱（XAS）和 X 射线磁圆二色性（XMCD）研究，分别对应于电子或空穴掺杂。从 XAS 光谱中 Cr 2p 吸收峰的形状可以得出结论，未掺杂、I 掺杂和轻度 N 掺杂样品中的 Cr 离子为二价（Cr(2+)），而在重度 N 掺杂样品中 Cr(2+) 和三价（Cr(3+))共存。这一结果表明，掺杂的氮原子充当受体，但掺杂的空穴位于 Cr 离子上。在 Cr 2p 吸收边的 XMCD 信号对磁场的依赖关系中，在未掺杂、I 掺杂和轻度 N 掺杂的样品中观察到了铁磁行为，而在重度 N 掺杂的样品中，铁磁行为被大大抑制，这与磁化测量的结果一致。
