Program Highlights

Electromechanical Switching in Graphene Nanoribbons

Renat Sabirianov and Wai-Ning Mei
Nebraska MRSEC

Properties of graphene, the strongest and most flexible as well as stretchable material can be tuned by mechanical deformations. In principle, by suitable engineering of local strain profiles, all-graphene electronics could be integrated on a single graphene sheet. Transport properties of graphene are very sensitive to mechanical deformations. For example, the bending of graphene films can enhance the film’s resistance, while the uniaxial stretching either enhances or reduces the film’s resistance. Furthermore, the uniaxial strain leads to the opening of the band gap in graphene. A number of spintronic devices such as a spin valve and a field-effect transistor were proposed. A moderate (~10%) magnetoresistance was observed at room temperature in a spin valve where graphene is sandwiched by two ferromagnetic electrodes. This research reports electromechanical switching in graphene nanoribbons (Carbon 51, 102-109 (2013)). Density-functional theory (DFT) calculations were used to investigate the effect of twisting on the electronic, magnetic and transport properties of zigzag graphene nanoribbon (ZGNR). The calculations showed that ZGNR in its antiferromagnetic ground state is insensitive to twisting and the conductance of the twisted ZGNR is almost unchanged. However, electromechanical switching can be realized by twisting a ferromagnetic ZGNR, which after twisting is an ideal spin valve in the case of oppositely polarized leads.  

These programs are supported by the National Science Foundation, Division of Materials Research, Materials Research Science and Engineering Program, Grant 0820521.

The spin structures of the antiferromagnetic (top) and the ferromagnetic twisted zigzag graphene nanoribbon (bottom) with a noncollinear magnetic domain wall.