Electric field control of soliton motion and stacking in trilayer graphene

The crystal structure of a material plays an important role in determining its electronic properties. Changing from one crystal structure to another involves a phase transition that is usually controlled by a state variable such as temperature or pressure. In the case of trilayer graphene, there are two common stacking configurations (Bernal and rhombohedral) that exhibit very different electronic properties. In graphene flakes with both stacking configurations, the region between them consists of a localized strain soliton where the carbon atoms of one graphene layer shift by the carbon-carbon bond distance. Here we show the ability to move this strain soliton with a perpendicular electric field and hence control the stacking configuration of trilayer graphene with only an external voltage. Moreover, we find that the free-energy difference between the two stacking configurations scales quadratically with electric field, and thus rhombohedral stacking is favoured as the electric field increases. This ability to control the stacking order in graphene opens the way to new devices that combine structural and electrical properties.M.Y. and B.J.L. were supported by the US Army Research Laboratory and the US Army Research Office under contract/grant number W911NF-09-1-0333. J.I-J.W. was partially supported by a Taiwan Merit Scholarship TMS-094-1-A-001. J.I-J.W and P.J-H. have been primarily supported by the US DOE, BES Office, Division of Materials Sciences and Engineering under Award DE-SC0001819. Early fabrication feasibility studies were supported by NSF Career Award No. DMR-0845287 and the ONR GATE MURI. This work made use of the MRSEC Shared Experimental Facilities supported by NSF under award No. DMR-0819762 and of Harvard’s CNS, supported by NSF under grant No. ECS-0335765. A.G.B. was supported by the US Army Research Laboratory (ARL) Director’s Strategic Initiative program on interfaces in stacked 2D atomic layered materials. P.S-J. received financial support from the Spanish Ministry of Economy (MINECO) through Grant no. FIS2011-23713, the European Research Council Advanced Grant (contract 290846) and from the European Commission under the Graphene Flagship (contract CNECT-ICT-604391)