EXCHANGE SPRING BEHAVIOR IN NANOCOMPOSITE HARD MAGNETIC-MATERIALS

The magnetic properties of nanocrystalline melt-spun single-phase (Nd2 Fe14B-type) and composite (Nd2Fe14B + alpha-Fe or Nd2Fe14B + Fe3B + al pha-Fe) magnets have been studied systematically in an attempt to unde rstand better their 'exchange spring' behavior. The reversibility of t he recoil demagnetization curves has been found to increase with incre asing content of the soft phase giving rise to the characteristic exch ange spring behavior only in nanocomposite samples. delta M plots indi cate positive interactions of the exchange type for small fields; for fields higher than the remanence coercivity, magnetostatic interaction s become dominant. The relative strength of the magnetostatic interact ions is increased in samples with higher soft phase contents.