Magnetic properties and structure of Nd-Fe-B thin films with Cr and Ti underlayers

We investigated the influence of the underlayers of Cr and Ti on the structure and magnetic properties of Nd-Fe-B thin films which were produced by a conventional RF sputtering method. The thickness of the underlayer and the substrate temperature were varied from 0 to 5000 Angstrom and from room temperature to 670 degrees C, respectively. It was found that the type and the thickness of the underlayer materials and the substrate temperature strongly influenced the crystal orientation and magnetic properties. The main crystalline phase was a Nd2Fe14B compound, whose tetragonal c-axis was aligned perpendicularly to the film plane. A high coercive force (H-c = 3.7 kOe) was achieved in the following conditions; Cr underlayer with the thickness of 500 Angstrom and the substrate temperature of 650 degrees C. (C) 1998 Elsevier Science B.V. All rights reserved.