I am a theoretical physicist interested in the electronic, optical and mechanical properties of a new class of materials, two-dimensional atomic crystals, and the related physical phenomena. Most of my work concerns graphene, the best known two-dimensional crystal, first obtained by mechanical exfoliation of graphite and made of a single layer of carbon atoms arranged in regular hexagons. I am also interested in the properties of other similar materials like transition metal dichalcogenides or phosphorene. Finally, I study properties of Van der Waals solids – new artificial materials built layer by atomic layer by stacking two-dimensional crystals on top of each other. Because of the high quality and atomic thickness of these materials, properties of such stacks are often more than a simple sum of the properties of the constituents.