Effect of 1.2 MeV argon ions irradiation on magnetic properties of ZnO

Abstract

Room temperature ferromagnetism in 1.2 MeV argon ions irradiated polycrystalline ZnO has been observed. The magnetic contribution in form of saturation magnetization is higher in sample irradiated with ion fluence of 1 × 1015 ions/cm2. However, annealing of the defects at higher fluences of 5 × 1015 ions/cm2 reduce the magnetic contribution in comparison to the magnetic contribution of the lower fluences. The X-ray diffraction reveals that the degree of crystallinity decreases with the increase of ion fluences upto 1 × 1015 ions/cm2 and further it increases at a fluence of 5 × 1015 ions/cm2. The inhomogeneous arrangement of grains and changes in their sizes with increasing ion fluences decrease the magnetic ordering of the system. The electron probe microstructure analyses and micro-Raman spectra of irradiated samples show in-homogeneity in zinc and oxygen ratio which is one of the causes to show ferromagnetism.