Our group at a glance
We are a computational physics / theory of materials group. We study the structure and properties of different phases of matter and how they can be used in practical device applications. We employ theoretical models and computational tools that span multiple scales from the atomistic to the continuum. We also use machine learning methods to search for new or better materials, and for gaining a deeper understanding of complex solids and phenomena (find out more in "Research").
A recent focus of our research has been the physics of twisted bilayers and multilayers of two-dimensional van der Waals (vdW) solids like graphene, a topic for which we introduced the term “twistronics”. This denotes the extraordinary behavior of electrons in twisted few-layer vdW solids, where the introduction of a new length scale by the twist angle produces localization, correlations, and interesting many-body physics. Our group was part of the collaboration that demonstrated correlated electron behavior and superconductivity in twisted bilayer graphene.
As examples, the figure above shows the atomic relaxation (exaggerated on the vertical axis) corresponding to a pattern of AA (red cones) and AB/BA (deep blue triangles) stacking regions, separated by domain boundaries (light blue lines). This pattern, introduced by the twist angle, produces the angle-dependent local density of states (LDOS) of electrons, shown in the figure below. The large LDOS enhancement is indicative of electron localization and is directly related to many-body physics in this system.