Influence of oxygen partial pressure on the microstructural and magnetic properties of Er-doped ZnO thin films

Abstract

Er-doped ZnO thin films have been prepared by using inductively coupled plasma enhanced physical vapor deposition at different O2:Ar gas flow ratio (R = 0:30, 1:30, 1:15, 1:10 and 1:6). The influence of oxygen partial pressure on the structural, optical and magnetic properties was studied. It is found that an appropriate oxygen partial pressure (R=1:10) can produce the best crystalline quality with a maximum grain size. The internal strain, estimated by fitting the X-ray diffraction peaks, varied with oxygen partial pressure during growth. PL measurements show that plenty of defects, especially zinc vacancy, exist in Er-doped ZnO films. All the samples show room-temperature ferromagnetism. Importantly, the saturation magnetization exhibits similar dependency on oxygen partial pressure with the internal strain, which indicates that internal strain has an important effect on the magnetic properties of Er-doped ZnO thin films.

Vickers microhardness and indentation creep studies for erbium-doped ZnO nanoparticles

“…Also, a diamagnetic and paramagnetic contribution appear in the hysteresis loop of pure ZnO sample at about 0.8 Tesla as M decreases with the increasing of H. This indicates the surface and ligand induced defects [39].The samples with x = 0.01 exhibits a room temperature ferromagnetism which may be caused by the substitution of Er 3+ in Zn 2+ sites rather due to the formation of any ferromagnetic secondary phase. Similar results were obtained by Chen et al [40] for Er-doped ZnO thin films prepared by coupled plasma enhanced physical vapor deposition. They reported that because the Er 2 O 3 powder has a paramagnetic property, it is logical to consider that the observed room temperature ferromagnetism is the intrinsic property of Er-doped ZnO films, and the ferromagnetism is a result of the substitution of Er 3+ in Zn 2+ sites.…”