Straining electromechanical coupling in layered crystals to new extremes

ended

"Inherent stability of layered 2D materials supports a remarkably large strain along the plane of these 1-atom-thick crystals. For example, graphene and MoS2 can stretch, in principle, by 20% - ten times more than the typical intrinsic breakdown strain of 3D crystals. Such extreme deformations of the interatomic distance can drive exciting structural phase transitions, support fascinating electronic orders, and pro-foundly impact the electronic or optical response. Individually, however, pulling these ultimately thin materials to reliably approach their intrinsic limit poses great challenge. Cracks, defects, and out-of-plane motion all motivate early rupture, that prevented ap-plicable demonstration of extreme strains so far. STRAIN2EXTREME, instead, relies on recent advances in Van-der-Waals (VdW) structures; Sandwiched between thin impermeable layers the mechanical stability is reinforced, while suppressing unwanted chemistry and contamination at these ""all-surface"" materials. Notably, the minute amount of defects, dangling bonds, and disorder, do not pin-down the strain to relax locally to the rigid substrate as in com-mon interfaces. It results in a nearly frictionless sliding between the weakly interacting layers. Based on this finding, I set forward an entirely new approach to pull the structures while supporting them on a “super-lubricant” substrate. This support allows us to gradually narrow the shape into sub-micrometre constrictions, and ""focus"" a moderate pulling force to induce extreme local strains reliably. Moreover, we directly control the gradient of the strain in space by the precise shape. Remarkably, fixed strain gradients, can induce uniform “pseudo-vector-potentials” of extreme strength. Using the unique mechanics and outstanding lubricity of VdW structure, I intend to realize highly ballistic time-reversal-protected transport, demonstrate a new ""pseudo-Hall"" effect, and explore crystal-induced electromagnetic fields in moire' super-lattices."