ERC FUNDED PROJECTS

Since its discovery, graphene has been indicated as a promising platform for quantum technologies (QT). The number of theoretical proposal dedicated to this vision has grown steadily, exploring a wide range of directions, ranging from spin and valley qubits, to topologically-protected states. The experimental confirmation of these ideas lagged so far significantly behind, mostly because of material quality problems. The quality of graphene-based devices has however improved dramatically in the past five years, thanks to the advent of the so-called van der Waals (vdW) heteostructures - artificial solids formed by mechanically stacking layers of different two dimensional (2D) materials, such as graphene, hexagonal boron nitride and transition metal dichalcogenides. These new advances open now finally the door to put several of those theoretical proposals to test. The goal of this project is to assess experimentally the potential of graphene-based heterostructures for QT applications. Specifically, I will push the development of an advanced technological platform for vdW heterostructures, which will allow to give quantitative answers to the following open questions: i) what are the relaxation and coherence times of spin and valley qubits in isotopically purified bilayer graphene (BLG); ii) what is the efficiency of a Cooper-pair splitter based on BLG; and iii) what are the characteristic energy scales of topologically protected quantum states engineered in graphene-based heterostructures. At the end of this project, I aim at being in the position of saying whether graphene is the horse-worth-betting-on predicted by theory, or whether it still hides surprises in terms of fundamental physics. The technological advancements developed in this project for integrating nanostructured layers into vdW heterostructures will reach even beyond this goal, opening the door to new research directions and possible applications.

1 806 250 €

Start date: 2019-09-01, End date: 2024-08-31

I propose to investigate the nanometer scale organization of delicate 2-dimensional molecular materials using nanoscale vibrational spectroscopy. 2D structures are of great scientific and technological importance, for example as novel materials (graphene, MoS2, WS2, etc.), and in the form of biological membranes and synthetic 2D-polymers. Powerful methods for their analysis and imaging with molecular selectivity and sufficient spatial resolution, however, are lacking. Tip-enhanced Raman spectroscopy (TERS) allows label-free spectroscopic identification of molecular species, with ≈10 nm spatial resolution, and with single molecule sensitivity for strong Raman scatterers. So far, however, TERS is not being carried out in liquids, which is the natural environment for membranes, and its application to poor Raman scatterers such as components of 2D polymers, lipids, or other membrane compounds (proteins, sugars) is difficult. TERS has the potential to overcome the restrictions of other optical/spectroscopic methods to study 2D materials, namely (i) insufficient spatial resolution of diffraction-limited optical methods; (ii) the need for labelling for all methods relying on fluorescence; and (iii) the inability of some methods to work in liquids. I propose to address a number of scientific questions associated with the spatial organization, and the occurrence of defects in sensitive 2D molecular materials. The success of these studies will also rely critically on technical innovations of TERS that notably address the problem of energy dissipation. This will for the first time allow its application to study of complex, delicate 2D molecular systems without photochemical damage.

2 311 696 €

Start date: 2017-09-01, End date: 2022-08-31

The field of C-H bond activation has evolved at an exponential pace in the last 15 years. What appeals most in those novel synthetic techniques is clear: they bypass the pre-activation steps usually required in traditional cross-coupling chemistry by directly metalating C-H bonds. Many C-H bond functionalizations today however, rely on poorly atom and step efficient oxidants, leading to significant and costly chemical waste, thereby seriously undermining the overall sustainability of those methods. As restrictions in sustainability regulations will further increase, and the cost of certain chemical commodities will rise, atom efficiency in organic synthesis remains a top priority for research. The aim of 2O2ACTIVATION is to develop novel technologies utilizing O2 as sole terminal oxidant in order to allow useful, extremely sustainable, thermodynamically challenging, dehydrogenative C-N and C-O bond forming coupling reactions. However, the moderate reactivity of O2 towards many catalysts constitutes a major challenge. 2O2ACTIVATION will pioneer the design of new catalysts based on the ultra-simple propene motive, capable of direct activation of O2 for C-H activation based cross-couplings. The project is divided into 3 major lines: O2 activation using propene and its analogues (propenoids), 1) without metal or halide, 2) with hypervalent halide catalysis, 3) with metal catalyzed C-H activation. The philosophy of 2O2ACTIVATION is to focus C-H functionalization method development on the oxidative event. Consequently, 2O2ACTIVATION breakthroughs will dramatically shortcut synthetic routes through the use of inactivated, unprotected, and readily available building blocks; and thus should be easily scalable. This will lead to a strong decrease in the costs related to the production of many essential chemicals, while preserving the environment (water as terminal by-product). The resulting novels coupling methods will thus have a lasting impact on the chemical industry.

1 489 823 €

Start date: 2017-03-01, End date: 2022-02-28

Topological insulators constitute a novel class of materials where the topological details of the bulk band structure induce a robust surface state on the edges of the material. While transport data for 2-dimensional topological insulators have recently become available, experiments on their 3-dimensional counterparts are mainly limited to photoelectron spectroscopy. At the same time, a plethora of interesting novel physical phenomena have been predicted to occur in such systems. In this proposal, we sketch an approach to tackle the transport and magnetic properties of the surface states in these materials. This starts with high quality layer growth, using molecular beam epitaxy, of bulk layers of HgTe, Bi2Se3 and Bi2Te3, which are the prime candidates to show the novel physics expected in this field. The existence of the relevant surface states will be assessed spectroscopically, but from there on research will focus on fabricating and characterizing nanostructures designed to elucidate the transport and magnetic properties of the topological surfaces using electrical, optical and scanning probe techniques. Apart from a general characterization of the Dirac band structure of the surface states, research will focus on the predicted magnetic monopole-like response of the system to an electrical test charge. In addition, much effort will be devoted to contacting the surface state with superconducting and magnetic top layers, with the final aim of demonstrating Majorana fermion behavior. As a final benefit, growth of thin high quality thin Bi2Se3 or Bi2Te3 layers could allow for a demonstration of the (2-dimensional) quantum spin Hall effect at room temperature - offering a road map to dissipation-less transport for the semiconductor industry.

2 419 590 €

Start date: 2011-04-01, End date: 2016-03-31