Influence of Additions and Stratification on the Magnetic Properties and Out-of-Plane Texture of Nd-Fe-B Films

Nd-Fe-B films with Ta and Mo additions used as buffer and capping layers and as interlayers have been deposited by r.f. sputtering on heated Si(111) substrates at 370 degrees C and 470 degrees C, and subsequently annealed at temperatures between 550 degrees C and 650 degrees C. In comparison with the Ta/NdFeB/Ta film, the Mo/NdFeB/Mo film deposited at 470 C presents an obvious anisotropic character. Very good anisotropic magnetic properties were obtained for Mo/[NdFeB(180)/Mo(5)]x3/Mo multilayer film deposited at 470 degrees C and then annealed at 550 degrees C. This sample exhibits an increase in coercivity from 1225 kA/m up to 1651.8 kA/m, increase in M-r/M-s ratio from 0.90 up to 0.99, and increase in the maximum energy product from 60.4 to 121.6 kJ/m(3) as compared to the as-deposited Mo/NdFeB/Mo film. The results demonstrate that after annealing at 550 degrees C the Mo film is more effective for nucleation of Nd2Fe14B hard magnetic grains with c-axis perpendicular to the film plane, especially in multilayer variant.