Semiconducting properties of a ferromagnetic nanocomposite: Fe@ZnO

The ferromagnetic and semiconducting nanocomposites, Fe@ZnO are prepared by ball milling technique. X-ray diffraction studies reveal that the average size of ZnO particles decreases with milling time, although the average size of Fe particles (16 nm) remains unaltered for the milling time 3–7 h. The optical band gap of ZnO estimated from UV–Vis spectra is found to be 3.2 eV which is almost independent of the particle size. Interestingly, this value is less than the value for the bulk counterpart. We note that this tailoring of band gap is observed in pure dilute magnetic semiconductor where Fe atom directly substitutes Zn atom. The nonlinear I–V curves have been found in the temperature range of 250–320 K. Analysis of the I–V curves infers that the inelastic tunneling is dominant in the conduction mechanism. The activation energy obtained from the voltage independent conductance is 0.30 eV, displaying the semiconducting properties. The detailed magnetization studies display the typical characteristic features of a soft ferromagnet at room temperature. (author)