Fabrication and Magnetic Properties of Exchange-Coupled Nd-Fe-B/Fe Nanocomposite Thin Films

Thin films which consist of randomly distributed Nd2Fe14B and Fe phases were fabricated on glass substrates by rf sputtering. With increasing a number of Fe chips on Nd-Fe-B target from 0 to 6, the remanence Br of the films increased from 6.4 to 15.6 kG, while the coercivity iHc reduced from 2.1 to 0.34 kOe at room temperature after annealing at 873 K for 10 min. In the case of Nd4.3Fe88.4B7.3 film, fabricated with 4 Fe chips, Br = 12 kG and iHc = 1.3 kOe were obtained and typical spring- back behavior was observed. Based on the temperature dependence of magnetization, volume fraction of &alpha-Fe phase was estimated to be VFe = 67 %. These results indicate the exchange coupling between Nd2Fe14B and Fe phases. The iHc value of the VFe = 67 % film is larger than that of recently fabricated Nd-Fe-B/α-Fe multilayer films with VFe =40∼50%.