  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 Li+3 ion
beam irradiation. The samples exhibit impurity phase and upon irradiation it
disappears. 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 (\chi-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.
