Electronic structure and magnetic studies of V-doped ZnO: ab initio and experimental investigations

Abstract

In this study, the electronic structure of V-doped ZnO system is studied by means of density functional theory. Different concentrations of V and rising of Fermi level increase the relative occupation of majority/minority spin of 3d state and also induce strong spin-splitting. The existence of three different states of V spin moment has been confirmed and is found to be concentration dependent. We found that O p-orbitals are responsible for the origin of the magnetic moment. Ruderman-Kittel-Kasuya-Yosida mechanism and the atomic spin polarization of V are the key factors for the appearance of ferromagnetism in V-doped ZnO system. The synthesized nanoparticles exhibit hexagonal wurtzite crystal structure, where both crystallite size and lattice parameters vary with V content. Magnetic measurements at room temperature confirm the ferromagnetic behaviour of V-doped ZnO system.

Grain growth kinetics and magnetic properties of a V-doped ZnO dilute magnetic oxide

“…7(b). The onset of the reduction of magnetization with increasing temperature at 270 K in the FC curve and at 240 K in the ZFC curve may be associated to the TC of some FM regions of the sample, probably due to different V concentrations as suggested by theoretical calculations of Mamouni et al [26] where the TC varies from 98 to 445 K for different V concentrations < 15 at.%. This issue will be analyzed later in this paper.…”

“…The highest saturation magnetization, Ms, of 0.9 Am -1 is obtained on the sample sintered at 1100 °C for 14 h. This low value of Ms is due to the existence of FM ordering only at the grain boundaries of the ceramic and at the proximity to the secondary phases (which can hinder the FM coupling). The maximum measured magnetization can be compared to other systems in the form of thin films (e.g., Ms = 11.22 Am -1 for a V concentration of 2 wt.% where V ions are homogeneously distributed [24]) or nanoparticles (with a magnetization of 1.68 Am -1 with a V concentration of 2 at.% [26]). It is important to note that in the ZnO:V system synthesized in form of thin films or nanoparticles, the magnetization depends on the concentration of the V magnetic ions.…”

Development of oxygen vacancies and surface defects in Mn-doped ZnO nanoflowers for enhancing visible light photocatalytic activity

“…The slight change in lattice parameters after 4% Mn doping into ZnO lattice was noted due to Mn ions which have smaller ionic radii (0.66 Å) than Zn ions (0.74 Å), it means a however small amount of Mn may change physical properties of ZnO material. Distortions may be developed in Mn-doped ZnO lattice owing to the approximately same ionic radii which reflects the change in lattice parameters in the system [24]. The average crystallite size of pure and Mn-doped ZnO samples was verified by employing the following formula [25].…”