Room temperature ferromagnetism in 200 KeV Nickel ion implanted Zinc oxide film

Abstract

Room temperature ferromagnetism is observed in 200 keV Ni (∼3%) implanted ZnO films deposited on Si (100) substrate by vapour phase transport process. Crystalline phases of ZnO and ZnO:Ni films are determined by grazing angle X-ray diffraction (GAXRD) technique. Using X-ray Fluroscence (XRF) technique the presence of Ni in ZnO matrix is detected. Magnetic measurement by alternating gradient magnetometer (AGM) shows a clear hysterisis loop at room temperature with a saturation magnetization of 0.025 emu/cm 3 , remnant magnetization of 0.0030 emu/cm 3 and coercive field of 53.14 Oe. Surface morphological study by atomic force microscope (AFM) of the films shows ∼73% enhancement of grain size and increase in surface areal density of grains. This is associated with almost 10 times reduction in resistivity value of the Ni implanted ZnO films as compared to its unimplanted counterpart as revealed by four probe resistivity technique. The result is understood on the basis of an exchange interaction of the charge carriers generated due to thermal effects of ion implantation and the localized spins of Ni.

Influence of microstructure on room temperature ferromagnetism in Ni implanted nanodimensional ZnO films

“…[9][10][11][12][13][14][15] In one of the reports, the origin of ferromagnetism was attributed to the presence of crystalline Ni nanoparticle. 11 In other studies, RT-FM was shown to be intrinsic in nature and explained by interaction of delocalized charge carriers with the localized magnetic moments of Ni.…”

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

“…As explained in our earlier works, 15,24,25 the implantation of Ni in the ZnO matrix creates different defects that eventually undergo a dynamical process due to thermal spikes generated inside the matrix during implantation. This was understood on the basis of the bound magnetic polaron model.…”