title: The mechanism of Al donor defects in (Zn, Co)O:Al: a view from resonant x-ray spectroscopies.
abstract: We studied the effect of Al doping in Zn(0.94)Co(0.05)Al(0.01)O nano-powders from the electronic structure point of view by applying x-ray absorption spectroscopy and resonant inelastic x-ray scattering at the oxygen K- and Co L-edges. The intensity of the pre-edge structure of the O-K XAS spectra is enhanced following the introduction of the Al defect. Multiple scattering calculations demonstrate it can be accounted for by the gain of the hybridization strength between O 2p and Al 3p (and/or Co 3d) states. The consensus on the hybridization strength is reached by combining Co-L XAS and RIXS investigations and multiplet calculations. It reveals different spatial substitutions of Al doping can alter the number of shared oxygen atoms between the Co and Al tetrahedrons. These shared ligands are responsible for the Al 3p and Co 3d state hybridization strength as well as the ferromagnetism of the ground state. The magnetic difference is better understood to be governed by various shared oxygen atoms rather than the distance between the Al defect and Co impurities.
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Beijing 100049, People's Republic of China.
authors.forename: K J
authors.initials: KJ
authors.lastname: Zhou
authors.forename: Y
authors.initials: Y
authors.lastname: Tezuka
authors.forename: M Q
authors.initials: MQ
authors.lastname: Cui
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: X C
authors.initials: XC
authors.lastname: Liu
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Chen
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Wu