Coercivity enhancement in La coated Nd-Fe-B thin films

摘要

The Nd-Fe-B/La thin films were deposited on the Al_2O_3(0001) substrate in order to investigate the effect of rare earth overlayer on the coercivity H_c. Highly textured Nd_2Fe_(14)B grains were grown by inserting the Mo(111) single crystal buffer layer. By depositing the La overlayer onto Nd2Fe_(14)B thin films and subsequently post-annealing at 470°CC, the H_c value increased from about 10.5 kOe to 15.0 kOe. The amount of H_c increase by the combination of the La coating and post-annealing was about 4.5 kOe. After the post annealing, La oxide (hcp La2O_3) was formed in the La layer, which was confirmed by means of XRD and SIMS depth profile measurements.