The role of Zn interstitials in cobalt-doped ZnO diluted magnetic semiconductors

摘要

Co-doped ZnO samples Zn_(1-x)Co_xO and Co_yZn_(1-y)O were prepared by the sol-gel and magnetron sputtering methods, respectively. Although the Co K-edge extended x-ray absorption fine structure spectra show that the doped Co ions are located at the Zn substitutional sites for both Zn_(1-x)Co_xO (x≤0.05) and Co_yZn_(1-y)O (y≤0.05) samples, magnetic measurements show paramagnetism in Zn_(1-x)Co_xO (x≤0.05) and high temperature ferromagnetism in Co_yZn_(1-y)O (y≤0.05). An experimental and numerical study of the O K-edge x-ray absorption near-edge structure spectra reveals that the incorporation of the Zn interstitials in the lattice is crucial to the appearance of high temperature ferromagnetism in Co_yZn_(1-y)O (y≤0.05) samples.