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RESEARCH PRODUCT

Nanomechanical cleavage of molybdenum disulphide atomic layers.

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description

The discovery of two-dimensional materials became possible due to the mechanical cleavage technique. Despite its simplicity, the as-cleaved materials demonstrated surprising macrocontinuity, high crystalline quality and extraordinary mechanical and electrical properties that triggered global research interest. Here such cleavage processes and associated mechanical behaviours are investigated by a direct in situ transmission electron microscopy probing technique, using atomically thin molybdenum disulphide layers as a model material. Our technique demonstrates layer number selective cleavage, from a monolayer to double layer and up to 23 atomic layers. In situ observations combined with molecular dynamics simulations reveal unique layer-dependent bending behaviours, from spontaneous rippling (o5 atomic layers) to homogeneous curving (B 10 layers) and finally to kinking (20 or more layers), depending on the competition of strain energy and interfacial energy.