We investigate the local structure of ferromagnetic Zn(1_x)CoxO epilayers by coupling polarization- dependent x-ray absorption spectroscopy and ab initio calculations of selected defect structures. We give clear evidence of the presence of oxygen vacancies, located close to the Co atoms in a specific complex configuration. We also establish the upper concentration limit of metallic parasitic nanophases and their contribution to magnetism. Our results lead to the conclusion that oxygen vacancies play an important role in originating the high temperature ferromagnetism of Zn(1_x)CoxO.
Cobalt-vacancy complexes and origin of ferromagnetism in Zn1-xCoxO dilute magnetic semiconductors
Paola Alippi
2012
Abstract
We investigate the local structure of ferromagnetic Zn(1_x)CoxO epilayers by coupling polarization- dependent x-ray absorption spectroscopy and ab initio calculations of selected defect structures. We give clear evidence of the presence of oxygen vacancies, located close to the Co atoms in a specific complex configuration. We also establish the upper concentration limit of metallic parasitic nanophases and their contribution to magnetism. Our results lead to the conclusion that oxygen vacancies play an important role in originating the high temperature ferromagnetism of Zn(1_x)CoxO.File in questo prodotto:
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