Molecular dynamics simulations on the wet/dry self-latching and electric fields triggered wet/dry transitions between nanosheets: A non-volatile memory nanostructure

We design a nanostructure composing of two nanoscale graphene sheets parallelly immersed in water. Using molecular dynamics simulations, we demonstrate that the wet/dry state between the graphene sheets can be self-latched; moreover, the wet→dry/dry→wet transition takes place when applying an external electric field perpendicular/parallel to the graphene sheets (E_⊥/E_||). This structure works like a flash memory device (a non-volatile memory):the stored information (wet and dry states) of the system can be kept spontaneously, and can also be rewritten by external electric fields. On the one hand, when the distance between the two nanosheets is close to a certain distance, the free energy barriers for the transitions dry→wet and wet→dry can be quite large. As a result, the wet and dry states are self-latched. On the other hand, an E_⊥ and an E_|| will respectively increase and decrease the free energy of the water located in-between the two nanosheets. Consequently, the wet→dry and dry→wet transitions are observed. Our results may be useful for designing novel information memory devices.