1. Key Laboratory for the Physics and Chemistry of Nanodevices and Department of ElectronicsPeking University Beijing 100871 P. R. China
2. Academy for Advanced Interdisciplinary StudiesPeking University Beijing 100871 P. R. China
3. Chongqing Key Laboratory of Multi‐scale Manufacturing TechnologyChongqing Institute of Green and Intelligent TechnologyChinese Academy of Sciences Chongqing 400714 P. R. China