Local Fe structure and ferromagnetism in Fe-doped ZnO films

Abstract

The local Fe structure and corresponding ferromagnetism are different for various concentrations of Fe-doped ZnO (Zn 1−x Fe x O, x = 0-0.07) films, which are prepared on LiNbO 3 (104) substrates by reactive magnetron sputtering. X-ray photoelectron spectroscopy and x-ray absorption near-edge structure (XANES) reveal that, when x 0.04, Fe is in the 2+ state and is incorporated into the wurtzite lattice of ZnO, and as x increases further, a second phase Fe 3 O 4 is induced. Furthermore, full multiple-scattering substitution ab initio calculation of Fe K -edge XANES is used to confirm the local structure of Fe in films with different x. The single-phase Fe-doped ZnO films (x 0.04) exhibit ferromagnetism above room temperature and the mechanism of bound magnetic polarons (BMPs) is proposed to discuss the magnetic properties. The presence of the second phase is responsible for the strong ferromagnetism for higher Fe concentration.

Structural, optical, and magnetic characterization of monodisperse Fe-doped ZnO nanocrystals

“…Cho et al 8 found ferromagnetic behavior in ͑Co, Fe͒-doped ZnO film grown by reactive magnetron cosputtering, where the effects of a rapid thermal annealing under vacuum lead to an increase in the magnetization and T C . Wei et al, 9 have deposited Fe-doped ZnO ͑Zn 1−x Fe x O, x = 0 -0.07͒ films onto LiNbO 3 substrate by magnetron sputtering and found that Fe substituted the Zn site in the 2 + charge state when x ഛ 0.04 leading to a strong ferromagnetism ͑T C ϳ 400 K͒. A further increase of the dopant atomic fraction up to 0.07 caused the precipitation of magnetite ͑Fe 3 O 4 ͒, which was conducive to the increase in the magnetic moment of the material.…”

Nanocrystalline Mn and Fe Doped ZnO Thin Films Prepared Using SILAR Method for Dilute Magnetic Semiconductor Application

“…When sensing of 300 ppm ethanol, the in situ extended X-ray absorption fine structure (EXAFS) spectra indicate that the bond distances of Zn-O and Fe-O are 1.90 and 1.98 Å, respectively and restored to 1.91 and 1.97 Å in the absence of ethanol (Hsu et al, 2007). The single-phase Fe-doped ZnO films (x≤0.04) exhibit ferromagnetism above room temperature (Wei et al, 2006). The Fe/ZnO composites display photoluminescence properties different from those of the ZnO entities generated similarly but in the absence of Fe powder: (i) a UV emission band is observed over the latter but not over the former, and (ii) the former shows an emission peak around 583 nm (wavelength) with intensity significantly stronger than that of the latter.…”

Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes

“…21 The electronic structure and the local environment of the GdZnO films were investigated by XAS measurements both at the O K-edge (resulting from O 1s ! 2p dipole transitions) and at the Gd M 4,5 -edge (3d !…”