The field of dilute magnetic semiconductors (DMS) is gaining increasing interest for the potential applications in spintronic devices, in which the spin degree of freedom of the charge carriers can be used to enhance the capabilities of conventional electronics, combining semiconducting and magnetic properties. Compounds based on ZnO, in particular ZnCoO, are especially appealing among DMS since they exhibit ferromagnetism at room temperature; however the origin of ferromagnetism in ZnCoO is still controversial. In this work, we use a synergic Co-edge X-ray absorption spectroscopy (XAS) and density functional theory calculations approach to perform a study of different kind of defects which could account for the magnetic behavior of ZnCoO. Our results suggest that a key role is played by specific defect complexes in which O vacancies are located close to the Co atoms1. Extended defects such as Co clusters have a marginal function, although we observe their formation at the epilayer surface under certain growth conditions2. Finally, we show preliminary results of the study of hydrogen-induced defects in ZnCoO epilayers deliberately hydrogenated via a Kaufman source. H is predicted to mediate a ferromagnetic spin-spin interaction between neighboring magnetic impurities. Co-edge XAS is supported by XRD, AFM, SEM, and VSM characterization.
Defect-induced magnetism in cobalt-doped ZnO epilayers
A Di Trolio;P Alippi;A Amore Bonapasta
2013
Abstract
The field of dilute magnetic semiconductors (DMS) is gaining increasing interest for the potential applications in spintronic devices, in which the spin degree of freedom of the charge carriers can be used to enhance the capabilities of conventional electronics, combining semiconducting and magnetic properties. Compounds based on ZnO, in particular ZnCoO, are especially appealing among DMS since they exhibit ferromagnetism at room temperature; however the origin of ferromagnetism in ZnCoO is still controversial. In this work, we use a synergic Co-edge X-ray absorption spectroscopy (XAS) and density functional theory calculations approach to perform a study of different kind of defects which could account for the magnetic behavior of ZnCoO. Our results suggest that a key role is played by specific defect complexes in which O vacancies are located close to the Co atoms1. Extended defects such as Co clusters have a marginal function, although we observe their formation at the epilayer surface under certain growth conditions2. Finally, we show preliminary results of the study of hydrogen-induced defects in ZnCoO epilayers deliberately hydrogenated via a Kaufman source. H is predicted to mediate a ferromagnetic spin-spin interaction between neighboring magnetic impurities. Co-edge XAS is supported by XRD, AFM, SEM, and VSM characterization.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
