Exchange bias in the nanogranular Fe/Feoxide system

The exchange bias effect has been investigated in a granular system composed of Fe particles (mean size 6 nm) embedded in an Fe oxide matrix. At T=5 K, the exchange field, the remanence and the coercivity have been found to strongly depend on the cooling field and on the temperature at which it is applied. The observed behavior is determined by the exchange coupling between the ferromagnetic nanoparticles and the magnetically disordered, cluster-glass-like matrix, whose spin configuration is affected by the field-cooling process.