1. Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500, USA
2. Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
3. HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen 518000, China
4. Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
5. Department of Physics and Astronomy, Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106, USA
6. Correlated Electronics Group, Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565, Japan
7. School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan