Soft X-ray Emission Spectra of Mn-doped ZnO Thin Films

The local electronic structures of Zn0.97Mn0.03O和Zn0.67Mn0.33O thin films prepared by a molecular beam epitaxy(MBE) at 200 ℃ were investigated by soft X-ray fluorescence spectrometer of beamline 8.0.1 of the Advanced Light Source(ALS).The special interest can be given to find the relationship between the electronic structure of Mn and magnetic properties of our samples.Analysis of the integral intensity ratio of Mn L2 to L3 emission lines(I(L2)/I(L3)) from resonant and nonresonant Mn L2,3 X-ray emission spectra(XES) indicates that ferromagnetism(FM) is related to the free d charge carriers in the film.For ferromagnetic Zn0.97Mn0.03O sample,the majority of Mn atoms are incorporated at Zn substitutional sites and the film shows strong Coster-Kronig(C-K) transitions due to a large amount of free charge carriers available around Mn atoms.Both non-localized d charge carriers as itinerant electrons and 4s electrons from interstitial Mn obtained by Ruderman-Kittel-Kasuya-Yosid(RKKY) calculations can induce the ferromagnetic exchange interaction.However,the disappearance of FM in Zn0.67Mn0.33O sample can be explained in terms of the existence of MnO clusters leading to a reduction in the number of free charge carriers.