Effects of Nd/Fe ratio on the microstructure and magnetic properties of NdFeB thin films

• Published in: Journal of magnetism and magnetic materials 2001-09, Vol.234 (3), p.489-493
• Main Authors: Kim, Y.B., Kim, M.J., Yang, J.H., Ryu, K.S., Li, Ying, Kim, T.K.
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Magnetic anisotropy; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Permanent magnet; Permanent magnets; Perpendicular anisotropy; Physics; Sputtering; Structure and morphology; thickness; Studies of specific magnetic materials; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(01)00422-X

The effects of composition on the microstructure and magnetic properties of NdFeB thin films synthesized by DC magnetron sputtering from targets of Nd 12.1Fe 80.4B 7.5 sintered magnet and Nd-chips have been investigated. The film with a compositional ratio of Nd/Fe=17.6/82.4 deposited at the substrate temperature T s=700°C showed soft magnetic properties with in-plane anisotropy. On increasing the compositional ratio to Nd/Fe=27/73, the coercivity increased to about i H c =1500 kA/m (∼18.9 kOe), and a columnar structure was formed with a strong perpendicular magnetic anisotropy. Further increase of the ratio to Nd/Fe=31/69 resulted in the increase of coercivity to about i H c =2070 kA/m (∼26 kOe). The microstructure, however, changed to spherical grains and the perpendicular magnetic anisotropy decreased. The change of substrate temperature also affected the magnetic properties. The film with Nd/Fe=27/73 deposited at a low temperature of T s=650°C showed high remanence with low coercivity. The increase of the temperature of T s=700°C resulted in high coercivity but low remanence.