1. 1) H. Fujimori, T. Masumoto, Y. Obi and M. Kikuchi: Jpn. J. Appl. Phys., 13 (1974), 1889.
2. 2) H. Fujimori, M. Kikuchi, Y. Obi and T. Masumoto: Sci. Rep. Res. Inst. Tohoku Univ., A26 (1976), 36.
3. 3) S. Ohnuma, K. Watanabe and T. Masumoto: Phys. Status Solidi, (a) 44 (1977), K151.
4. 4) Y. Makino, K. Aso, A. Uehira, M. Ito and M. Hayakawa: Inst. Electronics, Information Communication Engineers (IEICE) Technical Report, MR78-18 (1978), 39.
5. 5) T. Ojima, O. Kohmoto, K. Ohya and H. Fujishima: Bulletin of 11th Magnetics Society Japan (MSJ) Topical Symposium, 11-1 (1979), 83.