1. Department of Quantum Matter, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashihiroshima, Hiroshima 739-8530, Japan
2. Department of Low Temperature Experiment, Integrated Experimental Support/Research Division, N-BARD, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
3. ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom