1. Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530
2. Department of Electrical Engineering, Kure National College of Technology, Kure, Hiroshima 737-8506
3. Department of Applied Physics, Nagoya University, Nagoya 464-8603
4. The Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo 679-5198