Study of magnetic properties and local structures in discontinuous-CoFe-ZnO multilayers

In this study, we have investigated the magnetic properties and local structures of discontinuous-Co₇₀Fe₃₀(x Å)-ZnO multilayers (MLs). With the variation of Co₇₀Fe₃₀ nominal thickness, the phase transition from diluted magnetic semiconductor (DMS) phase, x=1 ML, to granular phase, x=5, and 9 MLs, is indicated from the measurements of magnetization versus temperature behavior and extended X-ray absorption fine structure (EXAFS) on Co or Fe K-edge. The analysis of EXAFS at Zn K-edge shows the reduction of Co coordination numbers with the increasing CoFe thickness. This result demonstrates that the CoFe grain size plays an important role in the formation of DMS and is greatly critical for multilayer growth technique.