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Molecular Magnetic Graphene Nanoribbons

Periodic Reporting for period 2 - MMGNRs (Molecular Magnetic Graphene Nanoribbons)

Reporting period: 2020-07-01 to 2021-12-31

Intense research efforts are currently aimed at establishing a fundamental link between spintronics, molecular electronics and quantum computation. Novel materials could usher a true revolution in this area, and magnetic graphene nanoribbons, in particular, have attracted impressive theoretical attention. However, creating them with the necessary level of precision has, until now, proved elusive, so that the extensive theoretical work remains fundamentally untested, and the applicative potential untapped. MMGNRs will investigate these uncharted waters, by developing a radically new approach: instead of the usual methods of cutting out graphene nanoribbons from large sheets, or randomly placing magnetic molecules on graphene surfaces, we will create graphene nanoribbons from a molecular bottom-up synthetic procedure, and attach molecular magnetic centres to their sides, at well-defined periodic intervals. In this way, a spin density is injected into the graphene backbone, and the homogeneity of the sample allows studying edge spin with unprecedented accuracy. MMGNRs will test the chemical possibilities offered by this approach, and will then use low-temperature transport and pulsed electron-paramagnetic-resonance spectroscopy to reveal the classical and quantum magnetic properties of graphene spin states. The success of MMGNRs will answer three fundamental questions: are our extensive theories of graphene magnetic states, for which there is no clean experimental counterpart, right? Can we use graphene magnetic states to perform quantum logic operations? Is it possible to push the quantum effects to high temperatures, and include them into electronic nanodevices? While answering these questions, MMGNRs will open a totally new area of chemical synthesis, redefine our experimental and theoretical knowledge of spins in graphene, and assess the limits and applicative potential of graphene and molecular spintronic devices.
We have:
1- Synthetized new graphene nanoribbons, with particular attention to: a) solubility issues; b) the creation of graphene nanoribbons with metal centres on the sides.
2- Managed to produce coordination compounds between metals and molecular graphene nanoribbons, with specific attention to: a) rare-earths; b) Cu(II)-based GNRs; c) Vanadyl-based complexes, for quantum applications.
3-investigated the quantum properties produced by the engineering of topological aromatic units.
4-investigated sources of decoherence, and implemented decouplign sequences for hyperfine interactions.
5- investigated the morphology-property relations, with particular attention to the chemical groups separating the nanoribbon edges and the spin-bearing centres, and to the morphology of graphenoids (e.g. wheels, small molecules etc...).
6-started a theoretical investigation of the nanoribbons, with atention to: a) the role and likelihood of occurrence of defects; b) the role of nanoribbon end sites; c) the role of the nanoribbon edges on topology.
7-created ultraclean electronic nanodevices that incorporate grphene nanoribbons with graphene electrodes.
8- identified electron-phonon processes, and Coulomb blockade events connected with Frank-Condon phenomena in the devices.
9-Created Single-Electron-Transistors that work up to room temperature from the graphene nanoribbons.
10-Created electronic nanodevices that include the same porphyrins that are attached onto the sides of the graphene nanoribbons, and demonstrated exchange-bias phenomena.
11- produced transport data and started data treatment for spin-resolved effects on the graphene nanoribbons observed via electron transport.
We are still ahead of competition on all aspects of the project. We have progressed enormously beyodn the state of the art, in all areas:
1-Syntheticaly, by creating a link between the organic synthetic techniques of polycyclic aromatic hydrocarbons and the coordination chemistry of transition and rare-earth metals.
2-In transport measurements, where we are achieving unprecedented results in spin transport phenomena.
3-In quantum materials, where we have demonstrated room teperature coherence times that allow creating novel quantum devices.

Because of delays introduced by external and uncontrollable factors, we plan to ask for a no-cost extension of the proposal.
A molecular spin-bearing graphene nanoribbon