Structure, energetic and tribological properties, and possible applications in NEMS of argon-separated double-layer graphene

The possibility to control the commensurability and distance between graphene layers separated by a dielectric spacer is considered by the example of a heterostructure consisting of double-layer graphene separated by atomic layers of argon. Van der Waals corrected density functional theory (DFT-D) is applied to study structural, energetic and tribological characteristics of this heterostructure. It is found that in the ground state, monolayer and bilayer argon spacers are incommensurate with the graphene layers, whereas submonolayer argon spacers which are commensurate with the graphene layers can exist only as metastable states. The calculations show that this incommensurability provides negligibly small static friction for relative motion of argon-separated graphene layers and, therefore, such a heterostructure holds great promise for the use in nanoelectromechanical systems. A scheme and operational principles of the nanorelay based on the revealed tribological properties of the heterostructure are proposed.