1. Department of Materials Science and Engineering, Kyoto University, Kyoto
606-8501
2. Department of Superconductivity, The University of Tokyo, Tokyo
113-8656
3. Neutron Scattering Laboratory, Institute for Solid State Physics,
The University of Tokyo,
Tokai, Ibaraki 319-1106
4. Advanced Research Center, Japan Atomic Energy Research Institute,
Tokai, Ibaraki 319-1195