Soft x-ray synchrotron radiation spectroscopy study of CuFe(1-x)Ni(x)O(2) (0 <= x <= 0.03) delafossite oxides

Abstract

Electronic structures of Ni-doped CuFe1-xNixO2 delafossite oxides (x = 0, 0.015, and 0.03) have been investigated by employing soft x-ray absorption spectroscopy and soft x-ray magnetic circular dichroism (XMCD). It is found that the valence states of Cu, Fe, and Ni ions are nearly monovalent (Cu+), trivalent (Fe3(+)), and divalent (Ni2+), respectively, and that they do not change with x. In contrast, the Cu 2p XMCD signals, which arise from the Cu2+ states, increase with increasing x. This study suggests that the increasing XMCD signals are presumably related to the formation of ferrimagnetic spinel impurities in CuFe1-xNixO2. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3561041]