Effect of Preparation Condition on Magnetic Properties of Nd-Fe-B/α-Fe Multi-layered Thick Film-Magnets Prepared by PLD Method

摘要

Nd-Fe-B/α-Fe multi-layered thick film-magnets were synthesized by PLD method from a Nd2.4Fe14B/α-Fe composite target. In order to improve magnetic properties and their reproducibility, effects of the stacking period of Nd-Fe-B/α-Fe layers, tp, the target-substrate distance, DTS, and the laser beam energy on a target, EL, on them were studied. The reproducibility of magnetic properties was improved significantly by decreasing LE. In particular, the standard deviation of the Nd content was suppressed within 3%, when LE was reduced from a value higher than 200 mJ/mm2 to 25 mJ/mm2. An increase in DTS and selection of a suitable tp value improved the maximum energy product (BH)max. The largest (BH)max value obtained in this investigation was 112 kJ/m3, which is higher than the values reported previously for isotropic film-magnets thicker than 10 μm. Origins of superior magnetic properties were discussed from the viewpoints of suitable interlayer exchange interaction between Nd-Fe-B and α-Fe layers and morphology of prepared film-magnets.