A Theoretical Analysis of Torque and Superlubric Motion in Bilayer Graphene Disks  

作　　者：LI Jianwen LIU Nianhua 

机构地区：[1]Institute for Advanced Study, Nanchang University [2]School of Science,Nanchang Institute of Technology

出　　处：《Wuhan University Journal of Natural Sciences》2015年第2期173-179,共7页武汉大学学报（自然科学英文版）

基　　金：Supported by the National Basic Research Program of China(973 Program)(2013CB934200);the Key Program of the National Natural Science Foundation of China(10832005);the National Natural Science Foundation of China(11264030)

摘　　要：To identify the relation between torque and superlubric motion, we investigate the interlayer sliding behavior of two graphene disks with numerical computation methods. The potential energy, lateral force and torque between the top and bottom graphene disks, which are associated with misfit angle, translational displacement and interlayer distance, are analyzed. The results show that the rotation of the top disk is feeble for commensurate state, but it is difficult to realize superlubricity due to the lateral force fluctuating remarkably. For incommensurate state, the flake exhibits vanishing torque approaching to zero only for partial sliding directions. The superlubricity between the top and bottom disks will be eliminated due to torque-induced reorientation along other sliding directions. Whether for commensurate or incommensurate contact, the amplitudes of the lateral force （516 pN and 13 pN, respectively） are in qualitative agreement with experimental observation （typically 250 pN and 50 pN, respectively）. It shows that the interlayer torque is insensitive to the top disk size with incommensurate contact. The results suggest that the superlubric motion of graphene disk can be controlled by adjusting the torque.To identify the relation between torque and superlubric motion, we investigate the interlayer sliding behavior of two graphene disks with numerical computation methods. The potential energy, lateral force and torque between the top and bottom graphene disks, which are associated with misfit angle, translational displacement and interlayer distance, are analyzed. The results show that the rotation of the top disk is feeble for commensurate state, but it is difficult to realize superlubricity due to the lateral force fluctuating remarkably. For incommensurate state, the flake exhibits vanishing torque approaching to zero only for partial sliding directions. The superlubricity between the top and bottom disks will be eliminated due to torque-induced reorientation along other sliding directions. Whether for commensurate or incommensurate contact, the amplitudes of the lateral force （516 pN and 13 pN, respectively） are in qualitative agreement with experimental observation （typically 250 pN and 50 pN, respectively）. It shows that the interlayer torque is insensitive to the top disk size with incommensurate contact. The results suggest that the superlubric motion of graphene disk can be controlled by adjusting the torque.

关 键 词：graphene disk incommensurate SUPERLUBRICITY TORQUE 

分 类 号：TB34[一般工业技术—材料科学与工程]