Project description
Angular control of 2D layer provides a path new path for valleytronics
In many 2D materials, electrons not only possess charge and spin, but further display an unusual quantum feature known as valley. While spintronics harnesses the electron spin to store, manipulate and read out information bits, the emerging field of valleytronics performs similar tasks using the multiple extrema of the band structure. The EU-funded TWISTRONICS project will investigate how to control and engineer these valley electronic states and phase transitions in graphene and boron nitride heterostructures by controlling a new degree of freedom, crystallographic alingment. The understanding of these states is highly relevant in the developing of future quantum technologies.
Objective
The relative angular alignment between the stacked 2D layers of a van der Waals (vdW) heterostructure can dramatically alter its fundamental properties. A striking example is the recent observation of strongly correlated states and intrinsic superconductivity in twisted bilayer graphene. Another remarkable effect of angular layer alignment predicted for certain vdW heterostructures is the emergence of phases of matter with non-trivial topological properties, where charge carriers flow without dissipation, being protected against perturbations. In graphene aligned with boron nitride (BN), such a phase has been predicted, with topological protection linked not to the spin, as commonly observed, but rather to the valley degree of freedom. However, due to the scarcity of experimental tools to demonstrate this topological protection, or tune the transition between topologically trivial and non-trivial phases, the few experimental observations available remain inconclusive.
The objective of TWISTRONICS is to contribute, with fundamental concepts, to future advancements of valleytronics, where the control over the valley degree of freedom is used for technological developments including quantum technologies. To reach this goal I propose a novel approach using dynamically rotatable heterostructures, combined with Berry curvature and real-space supercurrents distribution measurements, to tune and investigate the topological phases driven by crystal alignment on graphene/BN structures. This powerful triad will allow a rigorous investigation of the valley electronic states and phase transitions of this system, answering two important questions: i) What are the characteristics, origin and topology of the valley currents previously measured in graphene/BN aligned structures; and ii) how the valley currents and electron topology can be controlled by crystal axes alignment. This will trace a practical route to investigate and design topological phases in other vdW structures.
Fields of science
Not validated
Not validated
Programme(s)
Topic(s)
Funding Scheme
ERC-STG - Starting GrantHost institution
75794 Paris
France