TWISTM · Strongly correlated phenomena in twisted bilayers of graphene and transition metal dichacogenides

Strongly correlated phenomena in twisted bilayers of graphene and transition metal dichacogenides

The electronic properties of materials determine their potential use in commercial devices. Such electronic properties can be inferred by studying the electronic band structure - the allowed energy levels where electrons are. One way to create new band structures that host new states of matter is to change the crystalline environment. A crystal is a material where the atoms are arranged in an ordered manner. Depending on the details of the atoms environment, the band structure is going to be different. Two-dimensional materials, such as graphene and transition metal dichalcogenides, are crystalline structures that consist of a stack of one-atom-thick layers. They constitute a great platform to control the crystalline environment. Their layered structure enables their exfoliation down to the monolayer limit and their subsequent stacking to form vertical structures with novel properties. Both the choice of the materials that constitute each layer and how their are placed on top of each other allows for the design of the electronic properties of the full structure. Recent progress in the field has demonstrated that the combination of the constituents in the heterostructure is as important as the misalignment between the atomic layers for their performance. When to atomic layers are misaligned, a moiré pattern emerges. Such twist angle between the atomic layers strongly modifies the electronic band structure and new and exotic phases emerge that where absent in the individual elements. Correlated insulating states as well as superconductivity arises in twisted graphene structures at specific twist angles called 'magic angle'. Despite all this progress, however, research in this field is in its nascent stage and many exciting phenomena remain to be explored. In particular, the presence of other correlation-driven phases in twisted graphitic systems is unclear and the field needs a comprehensive understanding of the electronic phase diagram. The overall objective of TWISTM is to engineer samples with a twist angle between the constituents and study their electronic properties by means of low-temperature Scanning Tunneling Microscopy and Spectroscopy. Multiple two-dimensional materials will be explored, from semimetalic graphene to semiconducting transition metal dichalcogenides. The final goal is to understand the states of matter that emerge in moiré materials.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз