Probing origin of room temperature ferromagnetism in Ni ion implanted ZnO films with x-ray absorption spectroscopy

Abstract

Articles you may be interested inCoexistence of intrinsic and extrinsic origins of room temperature ferromagnetism in as implanted and thermally annealed ZnO films probed by x-ray absorption spectroscopy

Probing defect driven tunable spontaneous magnetization in paramagnetic Zn0.95Co0.05O epitaxial films by X-ray absorption investigations

“…2(b). The main absorption edge and its nearby spectral features for unirradiated and irradiated Zn 0.95 Co 0.05 O films are in stark contrast from Zn metal, which reveal predominant presence of Zn 2þ ions in wurtzite structure and ruled out the possibility of any significant metallic Zn cluster segregation [8,31]. However, for irradiated films particularly at higher fluences, marginal reduction at features B and slight shift of onset of absorption towards lower energy reveals enhancement in effective electron density of Zn atoms which can be associated either to the small fraction of Zn interstitials (Zn i ) or substituted Zn rich environment in the close vicinity of anionic vacancies.…”

Minority anion substitution by Ni in ZnO

“…1,2 ZnO doped with Ni (either during growth 3,4 or by ion implantation [5][6][7][8] ) is a good example of that, with similar magnetic behavior being ascribed to intrinsic ferromagnetic order in some cases, 3,5,6 and ferromagnetic secondary phases in others. 4,7,8 Since the magnetic behavior of a specific dopant-host combination is largely dependent on the material's local structure, the precise determination of the dopants' lattice location is crucial for the understanding of DMS materials.…”

“…The implantation was performed under a tilt angle of 17 • to minimize ion channeling, using an energy of 50 keV, resulting in a peak concentration of 7.0×10 18 cm −3 (0.017 atomic %) at a projected range of 231Å with a 109Å straggling, as estimated using SRIM. 18 In this low concentration regime, phase segregation and extended beam induced disorder are minimized, both of which occur for Ni concentrations in the atomic % range 6,8 (discussed in more detail below). Angular-dependent emission yields of the β − particles were measured at room temperature along , in the as-implanted state and after in situ capless annealing in vacuum (< 10 −5 mbar) at 300 • C, 600 • C and 900 • C. These patterns were recorded using a positionand energy-sensitive detection system similar to that described in Ref.…”

“…In ZnO doped with Ni (high doping regime, i.e. few atomic %) either during growth [9][10][11] or by ion implantation 6 , Ni has been found to substitute only the cation (Zn), based on extended X-ray absorption fine structure (XAFS) experiments. 6,[9][10][11] Making use of β − emission channeling, we have also observed pure Zn substitution by 3d transition metals, namely Fe 12 and Cu, 13 in the very dilute regime (< 0.02 atomic %).…”

“…few atomic %) either during growth [9][10][11] or by ion implantation 6 , Ni has been found to substitute only the cation (Zn), based on extended X-ray absorption fine structure (XAFS) experiments. 6,[9][10][11] Making use of β − emission channeling, we have also observed pure Zn substitution by 3d transition metals, namely Fe 12 and Cu, 13 in the very dilute regime (< 0.02 atomic %). However, for other 3d transition metals (Mn and Co) also in the very dilute regime, we have recently observed minority O substitution (∼ 20%), 14 which is remarkably unexpected based on the general understanding of lattice site preference of impurities in compound semiconductors.…”