1. Quantum Materials and Applications Research Center, National Institutes for Quantum Science and Technology, Takasaki, Gunma 370-1292, Japan
2. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
3. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
4. Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan
5. WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan