1. Nagoya University, Nagoya 464-8601, Japan
2. ATI, ULVAC, Inc., Chigasaki, Kanagawa 253-8543, Japan
3. Toyota Central R&D Labs., Inc., Nagakute, Aichi 480-1192, Japan
4. Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland