X-ray absorption, photoemission and electron spin resonance studies of Ar+ ion implanted ZnO

Defect induced room temperature ferromagnetism (RT-FM) in Ar+ implanted ZnO single crystal (ZnO-SC) is observe from the electron Spin Resonance (ESR) spectra and is correlated with their electronic structure studies using synchrotron radiation based X-ray absorption near edge structure (XANES) spectroscopy and valence band photoemission spectroscopy (VB-PES). Enhancement of absorption intensity at the edge of XANES spectra of Ar+ implanted ZnO indicates the increase of local density of states (DOS); which arises from the surface defects and/or dangling bonds in ZnO. VB-PES spectra change upon Ar+ implantation, becoming broader, implying the induced surface defects in ZnO-SC. X-ray photoelectron spectroscopy studies confirm that the Zn 2p3/2 core level peak shifts in lower energy side in Ar+ implanted ZnO-SC that is associated with the formation of oxygen vacancies/defects in ZnO-SC which is responsible for the RT-FM.