1. State Key Lab of New Ceramic and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China
2. Center for Advanced Mechanics and Materials CNMM Applied Mechanics Laboratory Department of Engineering Mechanics Tsinghua University Beijing 100084 China
3. School of Engineering Brown University Providence RI 02912 USA
4. State Key Laboratory of Tribology Tsinghua University Beijing 100084 China
5. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Science Beijing 100190 China