Affiliation: | (1) Institute for Solid State Physics, University of Tokyo, Minato-ku, Tokyo, Japan;(2) Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo, Japan;(3) Department of Physics, Tohoku University, Sendai, Japan;(4) Los Alamos Scientific Laboratory, Los Alamos, N.M., U.S.A.;(5) Bell Telephone Laboratories, Murray Hill, N.J., U. S. A. |