Characterization of magnetic components in the diluted magnetic semiconductor Zn1-xCoxO by x-ray magnetic circular dichroism -: art. no. 201201

We report on the results of x-ray absorption, x-ray magnetic circular dichroism (XMCD), and photoemission experiments on Zn1-xCoxO (x=0.05) thin film, which shows ferromagnetism at room temperature. The XMCD spectra show multiplet structures, characteristic of the Co2+ ion tetrahedrally coordinated by oxygen, suggesting that the ferromagnetism comes from Co ions substituting the Zn site in ZnO. The magnetic field and temperature dependences of the XMCD spectra imply that the nonferromagnetic Co ions are strongly coupled antiferromagnetically with each other.