Electronic structure and magnetism of the diluted magnetic semiconductor Fe-doped ZnO nanoparticles

Abstract

Articles you may be interested inEvidence of a cluster glass-like behavior in Fe-doped ZnO nanoparticles J. Appl. Phys. 115, 17E123 (2014) We have studied the electronic structure of Fe-doped ZnO nanoparticles, which have been reported to show ferromagnetism at room temperature, by x-ray photoemission spectroscopy, resonant photoemission spectroscopy, x-ray absorption spectroscopy, and x-ray magnetic circular dichroism ͑XMCD͒. From the experimental and cluster-model calculation results, we find that Fe atoms are predominantly in the Fe 3+ ionic state with mixture of a small amount of Fe 2+ and that Fe 3+ ions are dominant in the surface region of the nanoparticles. It is shown that the room temperature ferromagnetism in the Fe-doped ZnO nanoparticles primarily originated from the antiferromagnetic coupling between unequal amounts of Fe 3+ ions occupying two sets of nonequivalent positions in the region of the XMCD probing depth of ϳ2 -3 nm.

X-Ray Absorption Spectroscopy and X-Ray Magnetic Circular Dichroism Studies of Transition-Metal-Codoped ZnO Nano-Particles

“…In the nano-particle form, which has a relatively large surface area, the spin-orbit coupling and magnetic anisotropy may be enhanced due to surface effects. Indeed, this large M orb has been observed for ZnO:Fe nano-particles [9]. Figure 4(c) shows the Fe 2p→3d XMCD spectra taken in the TEY mode at various magnetic fields.…”

“…In the figures, we compare the experimental spectra (circles) taken both in the TEY and TFY modes with the cluster-model calculations for the Fe and Co ions with various valence states, tetrahedrally or octahedrally co-ordinated by oxygen atoms [21]. In the transitionmetal-doped ZnO nano-particles, the valence and the coordination of the doped atoms will be 2+(T d ) if no vacancies are created, or often become 3+(T d ) or 3+(O h ) due to the vacancy formation in the surfaces [7,9]. We therefore calculated spectra for the 2+(T d ), 3+(T d ), and 3+(O h ) states of the Fe and Co ions.…”

“…For example, high-valence (3+ and 4+) Mn and Co ions are found to be present in the surface of paramagnetic (Mn,Co)-codoped ZnO nano-particles [8], probably due to the formation of Zn vacancies (V Zn ) in the surface region. In the case of Fe-doped ZnO system, the doped Fe atoms are converted from 2+ to 3+ due to hole doping in the surface regions [7,9,16], resulting in the ferromagnetic interaction between the doped Fe atoms. In the case of Co-doped ZnO systems such as (Co,Ga)-codoped ZnO [10] and Co-doped ZnO nanoparticles [11], on the other hand, oxygen vacancies (V O ), which induce electron doping, are reported to be necessary for ferromagnetism.…”

Chemical bath deposition of Fe-doped ZnS thin films: Investigations of their ferromagnetic and half-metallic properties

“…Yet, it is still hard to say which is more reasonable. Moreover, some dispute still exists concerning the valency of iron ion and the origin of ferromagnetism in iron doped DMSs [24].…”

Fe doped ZnO thin film for mediator-less biosensing application

“…However, the presence of Fe 3þ ions is facilitated by the presence of surface oxygen interstitials. 16 The PL measurement suggests that the presence of excess oxygen in the form of antisite defects in the ZnO lattice which being electronegative supports the presence of Fe 3þ . The presence of both ions (Fe 2þ and Fe 3þ ) facilitates the electron transfer process by shuttling between the two oxidation states.…”