Effect of Preparation Condition on Magnetic Properties of ${\rm Nd-Fe-B}/\alpha -{\rm Fe}$ Multi-Layered Thick Film-Magnets Prepared by PLD Method

Nd-Fe-B/α-Fe multi-layered thick film-magnets were synthesized by pulse laser deposition (PLD) method from a Nd_2.4Fe₁₄B/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, t_p, the target-substrate distance, D_TS, and the laser beam energy on a target, E_L, on them were studied. The reproducibility of magnetic properties was improved significantly by decreasing E_L. In particular, the standard deviation of the Nd content was suppressed within 3%, when E_L was reduced from a value higher than 200 mJ/mm² to 25 mJ/mm² . An increase in D_TS and selection of a suitable t_p 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.