Interfacial magnetic phenomena of mechanosynthesized Fe nanoparticles in MnO matrix

Pure phase Fe/MnO nanocomposites are prepared by high energy ball-milling. Effect of crystallite size and milling induced defects on magnetic properties of nanocomposites are investigated. Mossbauer spectra have shown that Fe atoms in the nanocomposites are in ordered state up to 20 h milling duration. However, the appearance of a minor doublet in addition to a sextet in the Mössbauer spectrum of sample milled for 30 h has indicated polydispersity nature of the sample. The presence of exchange bias in the samples milled for higher durations are confirmed by magnetic hysteresis measurements. Temperature dependent ac and dc magnetization has indicated the presence of spin-glass like relaxation in the sample. This possibility has been confirmed by field cooled memory effect and temperature cycling in ZFC magnetization.