Structural modification by Li3+ ion irradiation and intrinsic magnetic properties of un-irradiated and Li3+ irradiated Zn0.96 Mn0.04O samples

• Impurity phase has been dissolved in 4 at.% Mn doped Zno bulk sample by 50 MeV Li3+ ion irradiation.
• Substitutional Mn incorporation in host ZnO matrix has been increased by Li ion beam irradiation.
• Ferromagnetism has been increased significantly by Li ion beam irradiation.
• We observed minor presence of superparamagnetic Mn nanoparticles.
• The main factor for ferromagnetism is contribution from intrinsic ZnO:Mn instead of any secondary phase.

Zn0.96Mn0.04O samples were synthesized by solid state reaction technique to explore their magnetic behavior. Structural, morphological and magnetic properties of the samples have been found to be modified by 50 MeV Li3+ ion beam irradiation. The samples exhibit impurity phase and upon irradiation it disappears. Li3+ ion irradiation has been utilized for increasing solubility limit of Mn in ZnO. Rietveld refinement analysis indicates that substitutional incorporation of Mn in the host lattice increases with irradiation. Grain size decreases with irradiation. Field dependent magnetization (M–H) measurement explicitly indicates ferromagnetic (FM) nature. It has been established from temperature dependent magnetization (M–T) measurement (500 Oe) and ac susceptibility (χ–T) measurement that ferromagnetism in the system seems to be mainly intrinsic; though superparamagnetic Mn nanoparticles also has a minor role. The analysis of M–T data at comparatively high field (5000 Oe) provides an estimation of antiferromagnetic (AFM) exchange, which acts as a reducing agent for observed magnetic moment. The value of saturation magnetization has been increased upon irradiation and is highly correlated with dissolution of impurity phase. Actually structural property has been modified with ion irradiation and this modification may cause some definite positive change in magnetic property of the sample.