1. Department of Electronics and Key Laboratory of Photo‐Electronic Thin Film Devices and Technology of Tianjin Nankai University Tianjin 300350 China
2. Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Department of Physics Tianjin University Tianjin 300072 China
3. School of Physics The University of Sydney NSW 2006 Australia
4. Physical Science and Engineering Division (PSE) King Abdullah University of Science and Technology (KAUST) Thuwal 23955‐6900 Saudi Arabia