Origin and control of room temperature ferromagnetism in Co,Zn-doped SnO2: oxygen vacancies and their local environment†
We combine quantitative X-ray spectroscopy and crystal field calculations to study Co and Zn co-doped SnO2 diluted magnetic semiconductor systems, report the location of vacancies, and the new effect of vacancy transfer resulting in optical luminescence only present after annealing. We connect this phenomenon to mid gap states using the band structure of the material obtained via density functional theory. Furthermore, we give a new understanding of the interaction of transition metals within co-doped systems. Finally, we present new evidence that the ferromagnetism is mediated by the oxygen vacancies and the particular local environment of the vacancies can be controlled via the synthesis conditions.