Modification of the Interface Nanostructure and Magnetic Properties in Nd-Fe-B Thin Films

Kunihiro Koike; Takanao Kusano; Daisuke Ogawa; Keisuke Kobayashi; Hiroaki Kato; Mikihiko Oogane; Takamichi Miyazaki; Yasuo Ando; Masaru Itakura

doi:10.1186/s11671-016-1227-x

Modification of the Interface Nanostructure and Magnetic Properties in Nd-Fe-B Thin Films

Nanoscale Res Lett. 2016 Dec;11(1):33. doi: 10.1186/s11671-016-1227-x. Epub 2016 Jan 19.

Authors

Kunihiro Koike¹, Takanao Kusano², Daisuke Ogawa³, Keisuke Kobayashi⁴, Hiroaki Kato⁵, Mikihiko Oogane⁶, Takamichi Miyazaki⁷, Yasuo Ando⁸, Masaru Itakura⁹

Affiliations

¹ Department of Applied Mathematics and Physics, Yamagata University, Yonezawa, 992-8510, Japan. kkoike@yz.yamagata-u.ac.jp.
² Department of Applied Mathematics and Physics, Yamagata University, Yonezawa, 992-8510, Japan. onakatanosaku@docomo.ne.jp.
³ Department of Applied Mathematics and Physics, Yamagata University, Yonezawa, 992-8510, Japan. d_ogawa@yz.yamagata-u.ac.jp.
⁴ Department of Applied Mathematics and Physics, Yamagata University, Yonezawa, 992-8510, Japan. koba0725keita@gmail.com.
⁵ Department of Applied Mathematics and Physics, Yamagata University, Yonezawa, 992-8510, Japan. kato@yz.yamagata-u.ac.jp.
⁶ Department of Applied Physics, Tohoku University, Sendai, 980-8579, Japan. oogane@mlab.apph.tohoku.ac.jp.
⁷ Department of Applied Physics, Tohoku University, Sendai, 980-8579, Japan. miyataka@tech.eng.tohoku.ac.jp.
⁸ Department of Applied Physics, Tohoku University, Sendai, 980-8579, Japan. ando@mlab.apph.tohoku.ac.jp.
⁹ Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, 816-8580, Japan. itakura@asem.kyushu-u.ac.jp.

Abstract

The effects of Nd2Fe14B grain size and Nd coating on the coercivity in sputter-deposited Nd-Fe-B/Nd thin films have been investigated in order to gain an insight into the coercivity mechanism of Nd-Fe-B magnets. Highly textured Nd2Fe14B particles were grown successfully on the MgO(100) single-crystal substrate with the Mo underlayer. As the Nd-Fe-B layer thickness t NFB was decreased from 70 to 5 nm, the coercivity H c increased gradually from 6.5 to 16 kOe. By depositing the Nd overlayer onto these films and post-annealing at 500 °C, the H c value further increased from 17.5 kOe (t NFB=70 nm) to 26.2 kOe (t NFB=5 nm). The amount of H c increase by the combination of the Nd coating and post-annealing was about 10 kOe irrespective of the t NFB value. These results therefore suggest an independence of size and interface effects on the coercivity of Nd-Fe-B magnets.

Keywords: Coercivity; Interface; Nd overlayer effect; Nd2Fe14B thin film.