Lapo Bogani: Topological effects in the quantum transport of molecular graphene nanoribbons

posted 27 May 2019, 07:59 by info admin
 Department of Materials, University of Oxford, Oxford, UK 

Fabricating devices that are nanometers long, yet defined down to the single-atom level, remains an enduring challenge in nanoscience. This degree of control is particularly appealing in graphene: graphene nanoribbons should produce field-effect-transistors with magnetic and topological effects solely when their edges are shaped with molecular precision.  Synthetic graphene nanoribbons now provide the necessary structural control, but their potential for quantum electronics remains unexplored. Here we report the observation of topological effects on the quantum transport of molecular graphene nanoribbons. The devices operate as ambi-polar transistors at room-temperature, and as single-electron transistors at low temperatures. Direct correspondence is established between the transport features and the morphology, with all features determined by the synthetic design. Molecularly-precise edges produce a magnetic field evolution that is completely opposite to non-molecular nanoribbons and the spin-orbit and coherent dephasing length are quantified, so that topology and time-reversal symmetry breaking become visible in a universality-class transition from symplectic to unitary. These results open the path to a new family of quantum electronic devices, where the graphene element can be atomically shaped, and synthetic chemistry allows the rational design of topological phenomena or applicative functionalities. 

Lapo Bogani obtained his PhD from the University of Florence, Italy. He moved to CNRS Grenoble with a personal Marie Curie fellowship, and then to Germany with a Sofja Kovalevskaja award of the Alexander von Humboldt Stiftung. In 2015 he moved to the University of Oxford with an ERC Starting Grant as Royal Society research fellow, and was appointed Professor in 2017. He is currently running an ERC Consolidator grant and he has been the recipient of a number of international awards, including the Kurti European research prize and the O. Kahn European award. His current research focuses on the transport and magnetic properties of molecular graphene nanostructures.