1. Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
2. Imec, Kapeldreef 75, 3001 Leuven, Belgium
3. Quantum Solid-State Physics Group, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
4. National Institute for Materials Science, Tsukuba 305-0047, Japan
5. Research Institute for Measurement and Analytical Instrumentation (RIMA), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
6. Research Center for Computational Design of Advanced Functional Materials (CD-FMat), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan