Coercivity enhancement of sputtered (La,Nd,Dy)-Fe-Co-B multilayers by inserting Ta space layers

Excellent magnetic properties of permanent magnets can be achieved by designing proper microstructure. In this work, we prepared (La-Nd-Dy)-Fe-Co-B single-layer and multilayers with different structures and found that the coercivity obtained for single-layer is 1.45 T and the optimum value for the coercivity of multilayer films increases to 1.95 T by inserting the metal Ta space layers. The enhancement of the coercivity in multilayer films originates from decoupling between Nd-Fe-B grains inserted by Ta space layers, less nucleation centers and the long-ranged magnetostatic interactions among different 2:14:1-type grains. Combining the micromagnetic analysis of the temperature dependence of coercivity and the magnetic domain evolutionary process at room temperature, the nucleation mechanism is confirmed as the dominant. This work is helpful for understanding the effect of microstructure on magnetic properties and the coercivity mechanism of high abundant rare earth permanent magnetic films.