1. State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Science Lanzhou 70000 China
2. Institute of Materials Science and Engineering Lanzhou University Lanzhou 730000 China
3. Division of Machine Elements Luleå University of Technology Luleå SE‐97187 Sweden
4. School of Nuclear Science and Technology University of South China Hengyang 421001 China
5. Department of Physics University of Basel Klingelbergstrasse 82 Basel 4056 Switzerland
6. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China