Nano-sized disorders in hard magnetic grains and their influence on magnetization reversal at artificial Nd/Nd2Fe14B interfaces

We have investigated the effect of lattice disorders near the surface of hard magnetic Nd2Fe14B grains on coercivity using artificial interfaces created by sputter depositing Nd on polished surface of Nd–Fe–B sintered magnets. The interfacial structure was manipulated by annealing the coated samples at 550 °C in vacuum with and without Ta cap. Nano-beam electron diffraction revealed a few nm thick disordered layer within the Nd2Fe14B phase at the Nd/Nd2Fe14B interface of a low coercivity sample, while a high coercivity sample showed a well-defined crystal structure of Nd2Fe14B near the NdOx/Nd2Fe14B interface.