1. Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China
2. Department of Engineering Mechanics, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
3. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
4. State Key Lab of Tribology in Advanced Equipment (SKLT), Tsinghua University, Beijing 10084, China
5. Institute of Superlubricity Technology, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
6. Tsinghua Shenzhen International Graduate School, Shenzhen 518057, China