1. Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601, Japan
2. Superconducting Properties Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
3. Superconducting Wires Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
4. Electrical and Electronic Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan