Understanding and controlling the behaviour of electrons in solids is a central challenge in condensed-matter physics. Many material properties arise from how electrons move, interact, and respond to their environment. Over the past decade, research on atomically thin, two-dimensional materials, most prominently the prototypical two-dimensional semimetal graphene, has demonstrated that reducing a material to only a few atomic layers can fundamentally alter electronic behaviour, enabling forms of quantum matter that do not exist in conventional bulk systems.
One approach to control electronic behaviour is the creation of superlattices, in which a periodically patterned structure is imposed on a material. Such structures modify electronic energy levels and dynamics by introducing an additional spatial length scale. In two-dimensional materials, superlattices have been shown to strongly affect electronic properties when the pattern period approaches the characteristic size of the electron wave. To date, however, these demonstrations have been largely restricted to a small number of material systems and specific patterning strategies.
Two-dimensional materials beyond graphene exhibit fundamentally different and highly tunable properties. Two-dimensional semiconductors, for example, typically host dilute electron gases whose density and energy landscape can be controlled using external electric fields. While interactions are weak in this regime, reshaping the electronic bands can enhance interaction effects and enable collective behaviour. Other materials host topologically protected electronic states or exhibit strong coupling between an electron’s motion and its spin. Accessing and controlling these properties requires approaches that go beyond existing methods.
This ERC Starting Grant project addresses this challenge by pursuing a top-down approach to superlattice engineering in two-dimensional van der Waals materials, based on fabrication techniques that allow nanoscale patterns to be defined with high precision. Because these materials are only a few atoms thick, externally defined structures can influence electronic states with high spatial fidelity. In contrast to approaches based on stacking layers, top-down patterning enables direct control over the geometry, symmetry, and strength of the imposed superlattice while maintaining electrical tunability.
The overall objectives of the project are to establish top-down superlattice engineering as a general strategy for controlling quantum behaviour in two-dimensional materials, to extend this concept beyond graphene to semiconductors, topological materials, and systems with strong spin-related effects, and to understand how engineered spatial structures can be used to induce and control new electronic states and collective phenomena.
