Nd-Ce-Fe-B core-shell magnets simulation by using Mumax3

The demagnetization curves as well as the magnetic moments distribution of two types of core-shell structure grains (core (Nd2Fe14B)-transition layer (Nd0.7Ce0.3)2Fe14B-shell (Ce2Fe14B) and core (Ce2Fe14B)-transition layer (Nd0.7Ce0.3)2Fe14B-shell (Nd2Fe14B)) have been investigated by three-dimensional (3D) micromagnetic calculations, focusing on the effect of the magnetic properties and demagnetization energy Ed under various core-shell components and transition layer thickness. As transition layer increases from 2 nm to 14 nm, the coercivity of both two types of grains decrease and the remanence and maximum energy product gradually increase; when the transition layers are the same, the magnetic properties of core (Nd2Fe14B) are higher than those of core (Ce2Fe14B). An increment of the transition layer thickness leads to a raise of the demagnetization energies (Ed) and the average magnetocrystalline anisotropy field, the demagnetization energy has a more significant impact on coercivity, thus the coercivity decreases. In the demagnetization process of core (Ce2Fe14B) structure grain, the magnetic moments of shell (Nd2Fe14B) deflects first, and the magnetic moments of the transition layer (Nd0.7Ce0.3)2Fe14B and the core (Ce2Fe14B) did not deflect under the external field before H = 66 kOe.