Impact of Li3+ ion irradiation on magnetic properties of Mn doped ZnO: correlation with defects and structural property

Abstract

Present work aims to study the impact of 50 MeV Li3+ ion irradiation on magnetic properties and their correlation with the substitutional incorporation of Mn at Zn site (MnZn) and defects in Mn:ZnO (Mn doped ZnO). 2 at% Mn:ZnO has been synthesized by solid-state reaction method and irradiated with fluences 1012, 1013 and 1014 ions/cm2. The concomitant changes have been probed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetization measurements. XRD patterns indicate single-phase nature of the samples and MnZn nicely varied with fluence of irradiation. Temperature dependent dc and ac magnetization (M-T) measurement reveals a minor presence of spin glass nature or superparamagnetism (SPM) though all of the samples are strongly intrinsically ferromagnetic and field dependent magnetization (M-H) measurement actually confirms this observation. It is noteworthy to observe that the ordering of spins and the magnetic parameters viz. saturation magnetization (MS), remnant magnetization (MR) and coercivity (HC) can be tuned by fluences of irradiation. Finally, proportion of defect [particularly zinc vacancy (VZn)] and MnZn seems to dictate the trend of variation of magnetization (MS and MR). Temperature dependent ac magnetization measurement and magnetic relaxation measurement actually detect a weak spin glass nature of the samples and eliminate the possibility of SPM.