Correlation between saturation magnetization and surface morphological features in Zn1−xCrxO thin films

Abstract

The effect of chromium doping on the defect-induced ferromagnetism of Zn1−xCrxO films was investigated in this study. X-ray diffraction and x-ray photoelectron results confirm Cr substitution at Zn sites in the ZnO host lattice. A parabolic dependence of the saturation magnetization on the stoichiometric variable x was observed. Photoluminescence and magnetic results indicate that magnetic moments in Zn1−xCrxO films stem from Zn vacancies on the film surface or at grain boundaries. As the variation in saturation magnetization is consistent with that in surface morphology, the ferromagnetism in Zn1−xCrxO films is sensitive to the morphological modification caused by Cr doping.

Antiferromagnetic coupling in Co-doped ZnS

“…Li et al [5] and Wang et al [16] have observed the decrease of magnetization with the increase of Cr doping concentration in ZnO and TiO 2 thin films, respectively. Hu et al [4] have also noticed decrease of magnetization with increase in Cr concentration in Zn 1-x Cr x O films. Thus, it can be concluded that the ferromagnetic nature in the Co-doped ZnS samples does not originate from the ferromagnetic nature of Co 2?…”

“…There have been many reports on roomtemperature ferromagnetism for wide bandgap semiconductor doped with a few percent of 3d transition-metal ions. The host materials for the DMS have been ZnO [1,[4][5][6], ZnS [2,[7][8][9][10][11][12], TiO 2 [13,14], SnO 2 [15,16], GaAs [17], AlN [18], and GaN [19]. TM-doped DMS materials always suffer from problems such as formation of secondary phase and/or clusters [2].…”

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

“…18 With the increase of P O2 , the intensity of the NBE peak diminishes rapidly due to the non-radiative recombination and lattice distortion. 12 The shoulder peak locating at 3.08 eV corresponding to V Zn emission 19 is also observed and the intensity of it decreases promptly with the increase of P O2 . Besides, two weak peaks locating at 2.85 eV (corresponding to Zn i emission) and 2.50 eV (corresponding to V o emission) [20][21][22] are also observed in EZO.…”

Zinc vacancy and erbium cluster jointly promote ferromagnetism in erbium-doped ZnO thin film

“…18 The blue shift of NBE emission peak position is attributed to Burstein-Moss effect. 19 A shoulder peak located at 3.08 eV corresponding to V Zn emission 8 is also observed and promptly decreases with the increase in x. The V Zn is formed through the substitution of Zn 2+ by Er 3+ , as follows:…”

“…Some researchers proposed that the ferromagnetism in TM doped ZnO was tuned by point defects such as oxygen vacancy (V o ), 6 zinc interstitial (Zn i ) 7 and zinc vacancy (V Zn ). 8 While other researchers reported that it was the metallic clusters rather than anything else that contributed to the ferromagnetism. 9,10 For the TM-doped ZnO thin films fabricated by unequilibrium deposition method, the point defects and TM clusters can coexist in the films at a proper situation.…”