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Under the terms of the Creative Commons Attribution License 3.0 (CC-BY). ; Zigzag graphene nanoribbons have spin-polarized edges, antiferromagnetically coupled in the ground state with total spin zero. Customarily, these ribbons are made ferromagnetic by producing an imbalance between the two sublattices. Here we show that zigzag ribbons can be ferromagnetic due to the presence of reconstructed divacancies near one edge. This effect takes place even though the divacancies are produced by removing two atoms from opposite sublattices, which were balanced before reconstruction to 5-8-5 defects. We demonstrate that there is a strong interaction between the defect-localized and edge bands which mix and split away from the Fermi level. This splitting is asymmetric, yielding a net edge spin polarization. Therefore, the formation of reconstructed divacancies close to the edges of the nanoribbons can be a practical way to make them partially ferromagnetic. ; This work was supported by the Polish National Science Center (Grant No. DEC-2011/03/B/ST3/00091), the Basque government through the NANOMATERIALS project (Grant No. IE05-151) under the ETORTEK Program iNanogune, the Spanish Ministry of Economy and Competitiveness MINECO (Grants No. FIS2013-48286-C2-1-P and No. FIS2012-33521), and the University of the Basque Country (Grant No. IT-366- 07). ; Peer Reviewed

In topological systems, a modulation in the gap onset near interfaces can lead to the appearance of massive edge states, as were first described by Volkov and Pankratov. In this work, we study graphene nanoribbons in the presence of intrinsic spin-orbit coupling smoothly modulated near the system edges. We show that this space modulation leads to the appearance of Volkov-Pankratov states, in addition to the topologically protected ones. We obtain this result by means of two complementary methods, one based on the effective low-energy Dirac equation description and the other on a fully numerical tight-binding approach, finding excellent agreement between the two. We then show how transport measurements might reveal the presence of Volkov-Pankratov states, and discuss possible graphenelike structures in which such states might be observed. ; The work of T.B. and D.B. was supported by the Spanish Ministerio de Ciencia, Innovation y Universidades (MICINN) through Project No. FIS2017-82804-P, and by the Transnational Common Laboratory Quantum-ChemPhys. M.R.C. acknowledges funding from the Spanish Government through Project No. MAT2017-88377-C2-2-R (AEI/FEDER) and the Generalitat Valenciana through Grant No. Cidegent2018004.

This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in ACS Nano, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acsnano.0c01837 ; The on-surface synthesis of edge-functionalized graphene nanoribbons (GNRs) is challenged by the stability of the functional groups throughout the thermal reaction steps of the synthetic pathway. Edge fluorination is a particularly critical case in which the interaction with the catalytic substrate and intermediate products can induce the complete cleavage of the otherwise strong C–F bonds before the formation of the GNR. Here, we demonstrate how a rational design of the precursor can stabilize the functional group, enabling the synthesis of edge-fluorinated GNRs. The survival of the functionalization is demonstrated by tracking the structural and chemical transformations occurring at each reaction step with complementary X-ray photoelectron spectroscopy and scanning tunneling microscopy measurements. In contrast to previous attempts, we find that the C–F bond survives the cyclodehydrogenation of the intermediate polymers, leaving a thermal window where GNRs withhold more than 80% of the fluorine atoms. We attribute this enhanced stability of the C–F bond to the particular structure of our precursor, which prevents the cleavage of the C–F bond by avoiding interaction with the residual hydrogen originated in the cyclodehydrogenation. This structural protection of the linking bond could be implemented in the synthesis of other sp2-functionalized GNRs ; C.M. was supported by the Agency for Management of University and Research grants (AGAUR) of the Catalan government through the FP7 framework program of the European Commission under Marie Curie COFUND action 600385 funded by the CERCA Program/Generalitat de Catalunya. We acknowledge support from the Spanish Ministry of Economy and Competitiveness, MINECO (under Contracts Nos. MAT2016-78293-C6 ...

Trabajo presentado al Symposium on Surface Science (3S), celebrado en Austria del 1 al 7 de marzo de 2020. ; Support by the European Union FET Open project SPRING (grant 863098) and by the Spanish Ministry of Economy and Competitiveness, MINECO (grants FIS2017-83780-P and MAT2016-78293-C6). ; Peer reviewed

[EN] Due to the increasing defect rates in highly scaled complementary metal-oxide-semiconductor (CMOS) devices, and the emergence of alternative nanotechnology devices, reliability challenges are of growing importance. Understanding and controlling the fault mechanisms associated with new materials and structures for both transistors and interconnection is a key issue in novel nanodevices. The graphene nanoribbon field-effect transistor (GNR FET) has revealed itself as a promising technology to design emerging research logic circuits, because of its outstanding potential speed and power properties. This work presents a study of fault causes, mechanisms, and models at the device level, as well as their impact on logic circuits based on GNR FETs. From a literature review of fault causes and mechanisms, fault propagation was analyzed, and fault models were derived for device and logic circuit levels. This study may be helpful for the prevention of faults in the design process of graphene nanodevices. In addition, it can help in the design and evaluation of defect- and fault-tolerant nanoarchitectures based on graphene circuits. Results are compared with other emerging devices, such as carbon nanotube (CNT) FET and nanowire (NW) FET. ; This work was supported in part by the Spanish Government under the research project TIN2016-81075-R and by Primeros Proyectos de Investigacion (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), under the project 200190032. ; Gil Tomás, DA.; Gracia-Morán, J.; Saiz-Adalid, L.; Gil, P. (2019). Fault Modeling of Graphene Nanoribbon FET Logic Circuits. Electronics. 8(8):1-18. https://doi.org/10.3390/electronics8080851 ; S ; 1 ; 18 ; 8 ; 8 ; International Technology Roadmap for Semiconductors (ITRS) 2013http://www.itrs2.net/2013-itrs.html ; Schuegraf, K., Abraham, M. C., Brand, A., Naik, M., & Thakur, R. (2013). Semiconductor Logic Technology Innovation to Achieve Sub-10 nm Manufacturing. IEEE Journal of the ...

Open-shell graphene nanoribbons have become promising candidates for future applications, including quantum technologies. Here, we characterize magnetic states hosted by chiral graphene nanoribbons (chGNRs). The substitution of a hydrogen atom at the chGNR edge by a ketone effectively adds one pz electron to the π-electron network, producing an unpaired π-radical. A similar scenario occurs for regular ketone-functionalized chGNRs in which one ketone is missing. Two such radical states can interact via exchange coupling, and we study those interactions as a function of their relative position, which includes a remarkable dependence on the chirality, as well as on the nature of the surrounding ribbon, that is, with or without ketone functionalization. Besides, we determine the parameters whereby this type of system with oxygen heteroatoms can be adequately described within the widely used mean-field Hubbard model. Altogether, we provide insight to both theoretically model and devise GNR-based nanostructures with tunable magnetic properties. ; We acknowledge financial support from the MCIN/AEI/10.13039/501100011033 (Grants PID2019-107338RB-C62, PID2019-107338RB-C63, PID2020-115406GB-I00, PCI2019-111933-2 (FLAG-ERA grant LEGOCHIP), and Juan de la Cierva Grant FJC2019-041202-I), the European Union's Horizon 2020 research and innovation program (FET-OPEN project SPRING, Grant No. 863098 and Marie Skłodowska-Curie Actions Individual Fellowship No. 101022150), the Xunta de Galicia (Centro Singular de Investigación de Galicia, 2019-2022, Grant ED431G2019/03), the European Regional Development Fund, the Basque Government (IT-1255-19), the Basque Government (PIBA Grant PI_2020_1_0014), the Basque Departamento de Educación through the Ph.D. scholarship No. PRE_2020_2_0049 (S.S.), the Spanish Research Council (LINKC20002). ; Peer reviewed

Trabajo presentado al International Workshop On-Surface Synthesis, celebrado en San Sebastián (España) del 27 al 30 de junio de 2016. ; Graphene nanoribbons (GNRs) make up an extremely interesting class of materials. On the one hand GNRs share many of the superlative properties of graphene, while on the other hand they display an exceptional degree of tunability of their optoelectronic properties. The presence or absence of correlated low-dimensional magnetism, or of a widely tunable band gap, is determined by the boundary conditions imposed by the width, crystallographic symmetry and edge structure of the nanoribbons. In combination with additional controllable parame-ters like the presence of heteroatoms, tailored strain, or the formation of hetero-structures, the possibilities to shape the electronic properties of GNRs according to our needs are fantastic. However, to really benefit from that tunability and harness the opportunities offered by GNRs, atomic precision is strictly required in their synthesis. This can be achieved through an on-surface synthesis approach, in which one lets appropriately designed precursor molecules to react in a selective way that ends up forming GNRs. In this chapter we review the structure-property relations inherent to GNRs, the synthesis approach and the ways in which the var-ied properties of the resulting ribbons have been probed, finalizing with selected examples of demonstrated GNR applications. ; Financial support by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 635919) and by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, Grant Nos. MAT2016-78293-C6-1-R, MAT2016-78293-C6-5-R and FIS 2015-62538-ERC) is acknowledged. ; Peer Reviewed

We report the on-surface synthesis of 7-armchair graphene nanoribbons (7-AGNRs) substituted with nitrile (CN) functional groups. The CN groups are attached to the GNR backbone by modifying the 7-AGNR precursor. Whereas many of these groups survive the on-surface synthesis, the reaction process causes the cleavage of some CN from the ribbon backbone and the on-surface cycloisomerization of few nitriles onto pyridine rings. Scanning tunneling spectroscopy and density functional theory reveal that CN groups behave as very efficient n-dopants, significantly downshifting the bands of the ribbon and introducing deep impurity levels associated with the nitrogen electron lone pairs. ; This work was supported by FP7 FET-ICT "Planar Atomic and Molecular Scale devices" (PAMS) project (funded by the European Commission under Contract No. 610446), by the Agencia Estatal de Investigacion (Cooperative Grant No. MAT2016-78293 and Grant FIS2015-62538-ERC), the Basque Government (Dep. de Educacion and UPV/EHU, Grant No. IT-756-13, and Dep. Industry, Grant PI_2015_1_42), the Xunta de Galicia (Centro singular de investigacion de Galicia accreditation 2016−2019, ED431G/09), and the European Regional Development Fund (ERDF). ; Peer Reviewed

Contributing to the need for new graphene nanoribbon (GNR) structures that can be synthesized with atomic precision, we have designed a reactant that renders chiral (3,1)-GNRs after a multistep reaction including Ullmann coupling and cyclodehydrogenation. The nanoribbon synthesis has been successfully proven on different coinage metals, and the formation process, together with the fingerprints associated with each reaction step, has been studied by combining scanning tunneling microscopy, core-level spectroscopy, and density functional calculations. In addition to the GNR's chiral edge structure, the substantial GNR lengths achieved and the low processing temperature required to complete the reaction grant this reactant extremely interesting properties for potential applications. ; The project leading to this publication has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 635919), from ICT-FET EU integrated project PAMS (Agreement No. 610446), from the Spanish Ministry of Science and Competitiveness (MINECO, Grant Nos. MAT2013-46593-C6-01, MAT2013-46593-C6-2-P, MAT2013-46593-C6-4-P, MAT2013-46593-C6-6-P), FEDER, from the Basque Government (Grant Nos. IT-621-13, IT-756-13, and PI2015-042), from the World Premier International Center (WPI) for Materials Nanoarchitectonics (MANA) of the National Institute for Materials Science (NIMS), Tsukuba, Japan, and from JSPS Bilateral Open Partnership Joint Research Project. ; Peer reviewed

Graphene nanoribbons (GNRs) and their derivatives attract growing attention due to their excellent electronic and magnetic properties as well as the fine-tuning of such properties that can be obtained by heteroatom substitution and/or edge morphology modification. Here, we introduce graphene nanoribbon derivatives—organometallic hybrids with gold atoms incorporated between the carbon skeleton and side Cl atoms. We show that narrow chlorinated 5-AGNROHs (armchair graphene nanoribbon organometallic hybrids) can be fabricated by on-surface polymerization with omission of the cyclodehydrogenation reaction by a proper choice of tailored molecular precursors. Finally, we describe a route to exchange chlorine atoms connected through gold atoms to the carbon skeleton by hydrogen atom treatment. This is achieved directly on the surface, resulting in perfect unsubstituted hydrogen-terminated GNRs. This will be beneficial in the molecule on-surface processing when the preparation of final unsubstituted hydrocarbon structure is desired. ; This work was supported by the National Science Center, Poland (2019/35/B/ST5/02666), and the EU Project PAMS (610446). A.G.L., D.S.P., and P.B. acknowledge the Spanish Agencia Estatal de Investigación (Grants MAT2016-78293-C6-4-R, PID2019-107338RB-C66, and FIS2017-83780-P), Dep. Educación of the Basque Government and UPV/EHU (Grant IT-756-13), and the European Union (EU) through Horizon 2020 (FET-Open project SPRING Grant 863098) for support. ; Peer reviewed

We report on the construction and magnetic characterization of a fully functional hybrid molecular system composed of a single magnetic porphyrin molecule bonded to graphene nanoribbons with atomically precise contacts. We use on-surface synthesis to direct the hybrid creation by combining two molecular precursors on a gold surface. High-resolution imaging with a scanning tunneling microscope finds that the porphyrin core fuses into the graphene nanoribbons through the formation of new carbon rings at chemically predefined positions. These ensure the stability of the hybrid and the extension of the conjugated character of the ribbon into the molecule. By means of inelastic tunneling spectroscopy, we prove the survival of the magnetic functionality of the contacted porphyrin. The molecular spin appears unaffected by the graphenoid electrodes, and we simply observe that the magnetic anisotropy appears modified depending on the precise structure of the contacts. ; We acknowledge the financial support from Spanish Agencia Estatal de Investigación (AEI) (project nos. MAT2016-78293-C6 and FIS2015-62538-ERC, and the Maria de Maeztu Units of Excellence Programme MDM-2016-0618), the Basque Government (Department Industry, grant no. PI-2015-1-42), the European project PAMS (610446), the Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2016 to 2019, ED431G/09), the European Research Council (grant agreement no. 635919), and the European Regional Development Fund. A ; Peer reviewed

We report on the construction and magnetic characterization of a fully functional hybrid molecular system composed of a single magnetic porphyrin molecule bonded to graphene nanoribbons with atomically precise contacts. We use on-surface synthesis to direct the hybrid creation by combining two molecular precursors on a gold surface. High-resolution imaging with a scanning tunneling microscope finds that the porphyrin core fuses into the graphene nanoribbons through the formation of new carbon rings at chemically predefined positions. These ensure the stability of the hybrid and the extension of the conjugated character of the ribbon into the molecule. By means of inelastic tunneling spectroscopy, we prove the survival of the magnetic functionality of the contacted porphyrin. The molecular spin appears unaffected by the graphenoid electrodes, and we simply observe that the magnetic anisotropy appears modified depending on the precise structure of the contacts. ; We acknowledge the financial support from Spanish Agencia Estatal de Investigación (AEI) (project nos. MAT2016-78293-C6 and FIS2015-62538-ERC, and the Maria de Maeztu Units of Excellence Programme MDM-2016-0618), the Basque Government (Department Industry, grant no. PI-2015-1-42), the European project PAMS (610446), the Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2016 to 2019, ED431G/09), the European Research Council (grant agreement no. 635919), and the European Regional Development Fund ; SI

This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes ; Recent advances in graphene-nanoribbon-based research have demonstrated the controlled synthesis of chiral graphene nanoribbons (chGNRs) with atomic precision using strategies of on-surface chemistry. However, their electronic characterization, including typical figures of merit like band gap or frontier band's effective mass, has not yet been reported. We provide a detailed characterization of (3,1)-chGNRs on Au(111). The structure and epitaxy, as well as the electronic band structure of the ribbons, are analyzed by means of scanning tunneling microscopy and spectroscopy, angle-resolved photoemission, and density functional theory ; The project leading to this publication has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 635919), from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grant nos. MAT2016-78293-C6, FIS2015-62538-ERC), from the Basque Government (grant nos. IT-621-13, PI-2015-1-42, PI-2016-1-0027), from the European Commission in FP7 FET-ICT "Planar Atomic and Molecular Scale Devices" (PAMS) project (contract no. 610446), from the Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2016−2019, ED431G/09), and from the European Regional Development Fund (ERDF)

Recent advances in graphene-nanoribbon-based research have demonstrated the controlled synthesis of chiral graphene nanoribbons (chGNRs) with atomic precision using strategies of on-surface chemistry. However, their electronic characterization, including typical figures of merit like band gap or frontier band's effective mass, has not yet been reported. We provide a detailed characterization of (3,1)-chGNRs on Au(111). The structure and epitaxy, as well as the electronic band structure of the ribbons, are analyzed by means of scanning tunneling microscopy and spectroscopy, angle-resolved photoemission, and density functional theory. ; The project leading to this publication has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 635919), from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grant nos. MAT2016-78293-C6, FIS2015-62538-ERC), from the Basque Government (grant nos. IT-621-13, PI-2015-1-42, PI-2016-1-0027), from the European Commission in FP7 FET-ICT "Planar Atomic and Molecular Scale Devices (PAMS) project (contract no. 610446), from the Xunta de Galicia (Centro singular de investigacion de Galicia accreditation 2016−2019, ED431G/09), and from the European Regional Development Fund (ERDF). ; Peer reviewed