Multilayer Magnets Original Research Article

After experimental evidence of intergrain exchange coupling was reported, nanocomposite magnets with high remanence and large energy products were predicted. However, the experimental values of the maximum magnetic energy product of nanocomposite bulk magnets have been much less than the theoretically predicted ones. We gave a brief review on advances in multilayer magnets. The exchange coupling and remanence enhancement were realized in nanocomposite (Nd,Dy)(Fe,Co,Nb,B)5,5/α-Fe thin films prepared by sputtering and heat treatments. Well-designed multilayer films consist of magnetically hard Nd2Fe14B-type phase with the grain size of 40 nm and magnetically soft α-Fe phase existing in the form of the continuous layers. Furthermore, we reported the structural and magnetic properties of anisotropic Nd-Fe-B thin films. The effects of thickness, deposition rates, substrate temperature, annealing temperature were studied. A high maximum energy product of (BH)max = 270 kJ/m3 was obtained for anisotropic Nd-Fe-B thin films.