Dr. Johann Coraux, Institut Néel, CNRS & Université Grenoble Alpes, Grenoble, France

Revisiting a few mechanics concepts with graphene on iridium: wrinkling, rippling, twisting
When two two-dimensional (2D) lattices interact, rich and sometimes intriguing order/disorder phenomena should be expected. A vast literature devoted to these questions dates back to the 1970s when monolayers-adsorbed-on-substrates were investigated, often with insightful parallels made with spin lattices. The strong cohesion of 2D materials, contrasting with the much weaker cohesion in more "conventional" 2D layers, brings additional behaviours that are reminiscent of those of membranes. The implications are altogether important for practical considerations regarding, e.g., the nature of the epitaxy in these systems, the formation of defects, or the intercalation underneath a 2D material, all of which have strong influence on the physical properties. The way the structure gets modulated in twisted 2D bilayers, and how this drives unique electronic / excitonic properties, is a recent popular example. I will address the case of (intercalated) graphene on Ir(111) -- not on the side of its (many) interesting electronic properties, but rather attempting to revisit a few nanomechanical and epitaxy concepts, in particular the issues of rippling and twisting.