1. Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
2. Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
3. RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
4. Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
5. Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 1, Zurich 8093, Switzerland
6. EMPA-Swiss Federal Laboratories for Materials Science and Technology, Uberlandstrasse 129, Dubendorf 8600, Switzerland