Structural, electrical and magnetic properties of Gd-doped and (Al, Gd) codoped ZnO films

Abstract

Gd-doped and (Al, Gd) codoped ZnO films were prepared by ion implantation and radio frequency magnetron sputtering. The resulting Gd-doped and (Al, Gd) codoped ZnO films were investigated with respect to their structural, electrical and magnetic properties. Room temperature ferromagnetism was obtained for all the doped films and the magnetization shows carrier concentration-dependent behavior. Two different regions can be divided in light of carrier concentration in which the bound magnetic polaron model and carrier-mediated exchange mechanisms produce a marked effect respectively in establishing the long-range ferromagnetic order. The first principle calculations reveal that the magnetic moment of (Al, Gd) codoped ZnO is higher than that of Gd-doped ZnO, and the ferromagnetic states of doped ZnO systems are more stable in the near configuration. Our results confirm that appropriate electron doping can effectively enhance the magnetic moment of the Gd-doped ZnO by controlling its concentrations, which may pave ways for preparing DMS with high magnetic moment using rare earth and group III elements as dopants.