Characterization of Magnetic Components in the Diluted Magnetic Semiconductor Zn$_{1-x}$Co$_x$O by X-ray Magnetic Circular Dichroism

摘要

We report on the results of x-ray absorption (XAS), x-ray magnetic circulardichroism (XMCD), and photoemission experiments on {it n}-typeZn$_{1-x}$Co$_x$O ($x=0.05$) thin film, which shows ferromagnetism at roomtemperature. The XMCD spectra show a multiplet structure, characteristic of theCo$^{2+}$ ion tetrahedrally coordinated by oxygen, suggesting that theferromagnetism comes from Co ions substituting the Zn site in ZnO. The magneticfield and temperature dependences of the XMCD spectra imply that thenon-ferromagnetic Co ions are strongly coupled antiferromagnetically with eachother.