Solid State Physics Seminar

Two-dimensional (2D) materials such as graphene and transitionmetal dichalcogenides offer new paradigms in condensed-matter physics.The weak van der Waals interactions that couple adjacent 2D materials inmultilayer assemblies mean that, contrary to conventional monolithicdevice such as Si-based architectures, the component layers possess atwist degree of freedom as well as a translation degree of freedom [1].The main implication of this is that designs with no true translationalsymmetry, but instead with aperiodic or quasicrystalline order, can beachieved. In this talk I will present an overview of the physics thatcan be unlocked in incommensurate systems and showcase two of our recentworks: the simulation of scanning tunnelling microscopy images in vander Waals systems which break translation symmetry [2], as well as ourrecent experimental discovery of directional superlubricity [3].[1] K. S. Novoselov et al., “2D materials and van der Waalsheterostructures”, Science 353 (629 (2016)[2] M. Le Ster et al., “Moiré plane wave expansion model for scanningtunneling microscopy simulations of incommensurate two-dimensionalmaterials”, Phys. Rev. B 110 (19), 195418 (2024)[3] M. Le Ster et al., “Evidence of directional structuralsuperlubricity and Lévy flights in a van der Waals heterostructure”,Small 21 (6), 2408349 (2024)