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1. Graphene oxide electrodes enable electrical stimulation of distinct calcium signalling in brain astrocytes

Author

Fabbri, Roberta, Scidà, Alessandra, Saracino, Emanuela, Conte, Giorgia, Kovtun, Alessandro, Candini, Andrea, Kirdajova, Denisa, Spennato, Diletta, Marchetti, Valeria, Lazzarini, Chiara, Konstantoulaki, Aikaterini, Dambruoso, Paolo, Caprini, Marco, Muccini, Michele, Ursino, Mauro, Anderova, Miroslava, Treossi, Emanuele, Zamboni, Roberto, Palermo, Vincenzo, and Benfenati, Valentina

Published
2024
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2. Bose-Einstein condensation of a two-magnon bound state in a spin-one triangular lattice

Author

Sheng, Jieming, Mei, Jia-Wei, Wang, Le, Jiang, Wenrui, Xu, Lei, Ge, Han, Zhao, Nan, Li, Tiantian, Candini, Andrea, Xi, Bin, Zhao, Jize, Fu, Ying, Yang, Jiong, Zhang, Yuanzhu, Biasiol, Giorgio, Wang, Shanmin, Zhu, Jinlong, Miao, Ping, Tong, Xin, Yu, Dapeng, Mole, Richard, Ma, Long, Zhang, Zhitao, Ouyang, Zhongwen, Tong, Wei, Podlesnyak, Andrey, Wang, Ling, Ye, Feng, Yu, Dehong, Wu, Liusuo, and Wang, Zhentao

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

Interactions of collective excitations often lead to rich emergent phenomena in many-particle quantum systems. In ordered magnets, the elementary excitations are spin waves (magnons), which obey Bose-Einstein statistics. Similar to the Cooper pairs in superconductors, magnons can be paired into bound states under attractive interactions. Even more interestingly, the Zeeman coupling to a magnetic field acts as a chemical potential that can tune the particle density through a quantum critical point (QCP), beyond which a ``hidden order'' is predicted to exist. However, experimental confirmation of this QCP and the associated new state of matter remain elusive. Here we report direct observation of the Bose-Einstein condensation (BEC) of the two-magnon bound state in Na$_2$BaNi(PO$_4$)$_2$. Comprehensive thermodynamic measurements confirmed the existence of a two-dimensional BEC-QCP at the saturation field. Inelastic neutron scattering experiments were performed to accurately establish the magnetic exchange model. An exact solution of the model found stable 2-magnon bound states that were further confirmed by an electron spin resonance (ESR) experiment, demonstrating that the QCP is due to the pair condensation and the phase below saturation field is the long-sought-after spin nematic (SN) phase., Comment: 53 pages, 28 figures

Published
2023

3. Author Correction: Graphene oxide electrodes enable electrical stimulation of distinct calcium signalling in brain astrocytes

Author

Fabbri, Roberta, Scidà, Alessandra, Saracino, Emanuela, Conte, Giorgia, Kovtun, Alessandro, Candini, Andrea, Kirdajova, Denisa, Spennato, Diletta, Marchetti, Valeria, Lazzarini, Chiara, Konstantoulaki, Aikaterini, Dambruoso, Paolo, Caprini, Marco, Muccini, Michele, Ursino, Mauro, Anderova, Miroslava, Treossi, Emanuele, Zamboni, Roberto, Palermo, Vincenzo, and Benfenati, Valentina

Published
2024
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4. Multiscale charge transport in van der Waals thin films: reduced graphene oxide as case study

Author

Kovtun, Alessandro, Candini, Andrea, Vianelli, Anna, Boschi, Alex, Elce, Simone Dell, Gobbi, Marco, Kim, Kyung Ho, Avila, Samuel Lara, Samori, Paolo, Affronte, Marco, Liscio, Andrea, and Palermo, Vincenzo

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Large area van der Waals (vdW) thin films are assembled materials consisting of a network of randomly stacked nanosheets. The multi-scale structure and the two-dimensional nature of the building block mean that interfaces naturally play a crucial role in the charge transport of such thin films. While single or few stacked nanosheets (i.e. vdW heterostructures) have been the subject of intensive works, little is known about how charges travel through multilayered, more disordered networks. Here we report a comprehensive study of a prototypical system given by networks of randomly stacked reduced graphene oxide 2D nanosheets, whose chemical and geometrical properties can be controlled independently, permitting to explore percolated networks ranging from a single nanosheet to some billions with room temperature resistivity spanning from 10-5 to 10-1 ohm m. We systematically observe a clear transition between two different regimes at a critical temperature T*: Efros-Shklovskii variable range hopping (ESVRH) below T* and power law (PL) behavior above. Firstly, we demonstrate that the two regimes are strongly correlated with each other, both depending on the charge localization length xi, calculated by ES-VRH model, which corresponds to the characteristic size of overlapping sp2 domains belonging to different nanosheets. Thus, we propose a microscopic model describing the charge transport as a geometrical phase transition, given by the metal-insulator transition associated with the percolation of quasi-1D nanofillers with length xi, showing that the charge transport behavior of the networks is valid for all geometries and defects of the nanosheets, ultimately suggesting a generalized description on vdW and disordered thin films.

Published
2021
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5. Structure-dependent electrical properties of graphene nanoribbon devices with graphene electrodes

Author

Martini, Leonardo, Chen, Zongping, Mishra, Neeraj, Barin, Gabriela Borin, Fantuzzi, Paolo, Ruffieux, Pascal, Fasel, Roman, Feng, Xinliang, Narita, Akimitsu, Coletti, Camilla, Müllen, Klaus, and Candini, Andrea

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Graphene nanoribbons (GNRs) are a novel and intriguing class of materials in the field of nanoelectronics, since their properties, solely defined by their width and edge type, are controllable with high precision directly from synthesis. Here we study the correlation between the GNR structure and the corresponding device electrical properties. We investigated a series of field effect devices consisting of a film of armchair GNRs with different structures (namely width and/or length) as the transistor channel, contacted with narrowly spaced graphene sheets as the source-drain electrodes. By analyzing several tens of junctions for each individual GNR type, we observe that the values of the output current display a width-dependent behavior, indicating electronic bandgaps in good agreement with the predicted theoretical values. These results provide insights into the link between the ribbon structure and the device properties, which are fundamental for the development of GNR-based electronics., Comment: Published in Carbon (2019)

Published
2019
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6. Molecules as Lubricants at the Nanoscale:Tunable Growth of Organic Structures from Nano‐ to Millimeter‐Scale Using Solvent Vapour Annealing.

Author

Benekou, Vasiliki, Candini, Andrea, Liscio, Andrea, and Palermo, Vincenzo

Subjects
*MONOMOLECULAR films, *SUPRAMOLECULAR chemistry, *MOLECULAR structure, *ORGANIC electronics, *SUBSTRATES (Materials science)
Abstract

The creation of ordered structures of molecules assembled from solution onto a substrate is a fundamental technological necessity across various disciplines, spanning from crystallography to organic electronics. However, achieving macroscopic order poses significant challenges, since the process of deposition is inherently impacted by factors like solvent evaporation and dewetting flows, which hinder the formation of well‐organized structures.Traditional methods like drop casting or spin coating encounter limitations due to the rapid kinetics of solvent evaporation, leading to limited control over final uniformity and order.In response to these challenges, Solvent Vapour Annealing (SVA) has emerged as a promising solution for realizing ordered molecular structures at scales ranging from nano‐ to milli‐ meters. SVA decouples the self‐assembly stage from the deposition stage by utilizing solvent vapours which can enable rearrangement, movement, and diffusion of large molecules on the surface even on a macroscopic scale. Essentially acting as “molecular lubricants,” solvent vapours enable the formation of well‐ordered molecular films. This review discusses the advancements, obstacles, and promising strategies associated with utilizing SVA for the development of innovative nanostructured thin films, and emphasizes the originality and effectiveness of molecular assembly on substrates achieved through this approach. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Laser-Patterned Polyurethane Composites with Graphene, Graphene Oxide, and Aramid Fibers for the Production of Electric Circuits, Sensors, and Heaters.

Author

Parkula, Vitaliy, Licata, Agata, Valorosi, Filippo, Kovtun, Alessandro, Scidà, Alessandra, Ruani, Giampiero, Liscio, Fabiola, Zanardi, Chiara, Candini, Andrea, Bertocchi, Francesco, Cristiano, Francesco, Brunella, Valentina, Cesano, Federico, Sarotto, Elio, Martorana, Brunetto, Treossi, Emanuele, and Palermo, Vincenzo

Abstract

The patterning of composites with carbon-based additives of nanometer or micrometer size was studied by the precise modification of material surfaces using laser technology. Initially, the composites are electrical insulators, but we can make them conductive by selective patterning; this process allows us to create conductive tracks within seconds, with a sheet resistance that can be adjusted over a wide range, from 108 Ω/sq down to 2.5 Ω/sq. The additives used include graphene nanoplatelets, graphene oxide nanosheets, and aramid fibers. By conducting microscopic and spectroscopic characterizations before and after laser treatment, we can distinguish between two different processes that lead to electrical conduction: (a) localized increase in the concentration of conductive additives or (b) localized reduction and pyrolysis of insulating additives. To demonstrate the versatility and usefulness of this technique in different fields of application, such as automotive, we fabricate three different devices on polyurethane: a heater, a proximity sensor, and an amperometric sensor for detecting biological analytes. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Quantum Sensing and Light Guiding with Fluorescent Nanodiamond‐Doped PVA Fibers.

Author

Styles, Roy, Candini, Andrea, Guarino, Vincenzo, Robertson, Islay, Singh, Priya, Cruz‐Maya, Iriczalli, Benfenati, Valentina, Abraham, Amanda N., Abe, Hiroshi, Ohshima, Takeshi, Broadway, David A., Greentree, Andrew D., Gibson, Brant C., Ambrosio, Luigi, Tetienne, Jean‐Philippe, and Reineck, Philipp

Subjects
*PHOTONS, *ELECTROMAGNETIC measurements, *OPTICAL measurements, *FIBERS, *NANODIAMONDS, *MAGNETIC resonance
Abstract

Fluorescent nanodiamonds (FNDs) containing quantum defects enable the optical measurement of electromagnetic fields and temperature and are among the most developed nanoscale quantum sensors today. Yet, for many applications in biomedicine and beyond, FNDs must be integrated into biocompatible substrates that preserve FND sensitivity and bring FNDs within nanoscale distance of their sensing target. At the same time, the high excitation light intensity required for most quantum sensing protocols remains a major challenge for applications in biomedicine. Here, it is shown that FNDs embedded in polyvinyl‐alcohol (PVA) fibers are a powerful 3D platform for nanoscale quantum sensing via light guiding. First, it is demonstrated that biocompatible PVA fibers can guide light to excite FNDs >10 µm from the excitation beam. Using this light‐guiding‐enabled excitation, optically detected magnetic resonance (ODMR) and T1 spin relaxometry measurements are performed using the nitrogen‐vacancy (NV) center in FNDs. Through ODMR thermometry, it is shown that light‐guiding‐enabled excitation mitigates light‐induced heating. Finally, the quantum sensing capability of the platform is established by detecting paramagnetic gadolinium in a dry and aqueous environment using T1 relaxometry of the NV center in FNDs. These results pave the way for light‐guiding‐enabled optical quantum sensing in biomedicine using nanodiamond‐doped biosubstrates. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Quantum Sensing and Light Guiding with Fluorescent Nanodiamond‐Doped PVA Fibers

Author

Styles, Roy, primary, Candini, Andrea, additional, Guarino, Vincenzo, additional, Robertson, Islay, additional, Singh, Priya, additional, Cruz‐Maya, Iriczalli, additional, Benfenati, Valentina, additional, Abraham, Amanda N., additional, Abe, Hiroshi, additional, Ohshima, Takeshi, additional, Broadway, David A., additional, Greentree, Andrew D., additional, Gibson, Brant C., additional, Ambrosio, Luigi, additional, Tetienne, Jean‐Philippe, additional, and Reineck, Philipp, additional

Published
2023
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12. Native Silicon Oxide Properties Determined by Doping

Author

Della Ciana, Michele, primary, Kovtun, Alessandro, additional, Summonte, Caterina, additional, Candini, Andrea, additional, Cavalcoli, Daniela, additional, Gentili, Denis, additional, Nipoti, Roberta, additional, and Albonetti, Cristiano, additional

Published
2023
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13. Insight on the Intracellular Supramolecular Assembly of DTTO: A Peculiar Example of Cell‐Driven Polymorphism

Author

Aloisio, Ludovico, primary, Moschetta, Matteo, additional, Boschi, Alex, additional, Fleitas, Ariel García, additional, Zangoli, Mattia, additional, Venturino, Ilaria, additional, Vurro, Vito, additional, Magni, Arianna, additional, Mazzaro, Raffaello, additional, Morandi, Vittorio, additional, Candini, Andrea, additional, D'Andrea, Cosimo, additional, Paternò, Giuseppe Maria, additional, Gazzano, Massimo, additional, Lanzani, Guglielmo, additional, and Di Maria, Francesca, additional

Published
2023
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14. Spin-enhanced magnetocaloric effect in molecular nanomagnets

Author

Evangelisti, Marco, Candini, Andrea, Ghirri, Alberto, Affronte, Marco, Brechin, Euan K., and McInnes, Eric J. L.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

An unusually large magnetocaloric effect for the temperature region below 10 K is found for the Fe14 molecular nanomagnet. This is to large extent caused by its extremely large spin S ground-state combined with an excess of entropy arising from the presence of low-lying excited S states. We also show that the highly symmetric Fe14 cluster core, resulting in small cluster magnetic anisotropy, enables the occurrence of long-range antiferromagnetic order below T_N=1.87 K., Comment: 4 pages, 3 figures, accepted for publication in Applied Physics Letters

Published
2005
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15. Mesoscopic 3D Charge Transport in Solution‐Processed Graphene‐Based Thin Films: A Multiscale Analysis

Author

Boschi, Alex, primary, Kovtun, Alessandro, additional, Liscio, Fabiola, additional, Xia, Zhenyuan, additional, Kim, Kyung Ho, additional, Avila, Samuel Lara, additional, De Simone, Sara, additional, Mussi, Valentina, additional, Barone, Carlo, additional, Pagano, Sergio, additional, Gobbi, Marco, additional, Samorì, Paolo, additional, Affronte, Marco, additional, Candini, Andrea, additional, Palermo, Vincenzo, additional, and Liscio, Andrea, additional

Published
2023
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16. Spontaneous Coassembly of the Protein Terthiophene into Fluorescent Electroactive Microfibers in 2D and 3D Cell Cultures

Author

Palamà, Ilaria Elena, Maiorano, Gabriele, Di Maria, Francesca, Zangoli, Mattia, Candini, Andrea, Zanelli, Alberto, D’Amone, Stefania, Fabiano, Eduardo, Gigli, Giuseppe, Barbarella, Giovanna, Palamà, Ilaria Elena, Maiorano, Gabriele, Di Maria, Francesca, Zangoli, Mattia, Candini, Andrea, Zanelli, Alberto, D'Amone, Stefania, Fabiano, Eduardo, Gigli, Giuseppe, and Barbarella, Giovanna

Subjects
General Chemical Engineering, General Chemistry
Abstract

Protein-based microfibers are biomaterials of paramount importance in materials science, nanotechnology, and medicine. Here we describe the spontaneous in situ formation and secretion of nanostructured protein microfibers in 2D and 3D cell cultures of 3T3 fibroblasts and B104 neuroblastoma cells upon treatment with a micromolar solution of either unmodified terthiophene or terthiophene modified by mono-oxygenation (thiophene → thiophene S-oxide) or dioxygenation (thiophene → thiophene S,S-dioxide) of the inner ring. We demonstrate via metabolic cytotoxicity tests that modification to the S-oxide leads to a severe drop in cell viability. By contrast, unmodified terthiophene and the respective S,S-dioxide cause no harm to the cells and lead to the formation and secretion of fluorescent and electroactive protein-fluorophore coassembled microfibers with a large aspect ratio, a micrometer-sized length and width, and a nanometer-sized thickness, as monitored in real-time by laser scanning confocal microscopy (LSCM). With respect to the microfibers formed by unmodified terthiophene, those formed by the S,S-dioxide display markedly red-shifted fluorescence and an increased n-type character of the material, as shown by macroscopic Kelvin probe in agreement with cyclovoltammetry data. Electrophoretic analyses and Q-TOF mass spectrometry of the isolated microfibers indicate that in all cases the prevalent proteins present are vimentin and histone H4, thus revealing the capability of these fluorophores to selectively coassemble with these proteins. Finally, DFT calculations help to illuminate the fluorophore-fluorophore intermolecular interactions contributing to the formation of the microfibers.

Published
2022

17. Core–Shell Architecture in Poly(3-hexylthiophene) Nanoparticles: Tuning of the Photophysical Properties for Enhanced Neuronal Photostimulation

Author

Barsotti, Jonathan, primary, Perotto, Sara, additional, Candini, Andrea, additional, Colombo, Elisabetta, additional, Camargo, Franco V. A., additional, Di Marco, Stefano, additional, Zangoli, Mattia, additional, Sardar, Samim, additional, Barker, Alex J., additional, D’Andrea, Cosimo, additional, Cerullo, Giulio, additional, Rozen, Shlomo, additional, Benfenati, Fabio, additional, Di Maria, Francesca, additional, and Lanzani, Guglielmo, additional

Published
2023
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18. Photoreactivity of Thiophene-Based Core@Shell Nanoparticles: The Effect of Photoinduced Charge Separation on In Vivo ROS Production

Author

Zangoli, Mattia, primary, Cantelli, Andrea, additional, Candini, Andrea, additional, Lewinska, Anna, additional, Fardella, Federica, additional, Tino, Angela, additional, Tommasini, Giuseppina, additional, Wnuk, Maciej, additional, Moschetta, Matteo, additional, Perotto, Sara, additional, Lucarini, Marco, additional, Tortiglione, Claudia, additional, Lanzani, Guglielmo, additional, and Di Maria, Francesca, additional

Published
2023
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20. Two-dimensional quantum universality in the spin-1/2 triangular-lattice quantum antiferromagnet Na 2 BaCo(PO 4 ) 2

Author

Sheng, Jieming, primary, Wang, Le, additional, Candini, Andrea, additional, Jiang, Wenrui, additional, Huang, Lianglong, additional, Xi, Bin, additional, Zhao, Jize, additional, Ge, Han, additional, Zhao, Nan, additional, Fu, Ying, additional, Ren, Jun, additional, Yang, Jiong, additional, Miao, Ping, additional, Tong, Xin, additional, Yu, Dapeng, additional, Wang, Shanmin, additional, Liu, Qihang, additional, Kofu, Maiko, additional, Mole, Richard, additional, Biasiol, Giorgio, additional, Yu, Dehong, additional, Zaliznyak, Igor A., additional, Mei, Jia-Wei, additional, and Wu, Liusuo, additional

Published
2022
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22. Push–pull thiophene-based small molecules with donor and acceptor units of varying strength for photovoltaic application: beyond P3HT and PCBM

Author

Marinelli, Martina, Candini, Andrea, Monti, Filippo, Boschi, Alex, Zangoli, Mattia, Salatelli, Elisabetta, Pierini, Filippo, Lanzi, Massimiliano, Zanelli, Alberto, Gazzano, Massimo, Di Maria, Francesca, Marinelli, Martina, Candini, Andrea, Monti, Filippo, Boschi, Alex, Zangoli, Mattia, Salatelli, Elisabetta, Pierini, Filippo, Lanzi, Massimiliano, Zanelli, Alberto, Gazzano, Massimo, and Di Maria, Francesca

Subjects
photovoltaic, thiophene, electrochemistry, push-pull molecules, oligomer, density functional theory
Abstract

Here is reported an expedient synthesis implementing enabling technologies of a family of thiophene-based heptamers alternating electron donor (D) and acceptor (A) units in a D-A '-D-A-D-A '-D sequence. The nature of the peripheral A groups (benzothiadiazole vs. thienopyrrole-dione vs. thiophene-S,S-dioxide) and the strength of the donor units (alkyl vs. thioalkyl substituted thiophene ring) have been varied to finely tune the chemical-physical properties of the D-A oligomers, to affect the packing arrangement in the solid-state as well as to enhance the photovoltaic performances. The optoelectronic properties of all compounds have been studied by means of optical spectroscopy, electrochemistry, and density functional theory calculations. Electrochemical measurements and Kelvin probe force microscopy (KPFM) predicted a bifunctional behaviour for these oligomers, suggesting the possibility of using them as donor materials when blended with PCBM, and as acceptor materials when coupled with P3HT. Investigation of their photovoltaic properties confirmed this unusual characteristic, and it is shown that the performance can be tuned by the different substitution pattern. Furthermore, thanks to their ambivalent character, binary non-fullerene small-molecule organic solar cells with negligible values of HOMO and LUMO offsets were also fabricated, resulting in PCEs ranging between 2.54-3.96%.

Published
2021

24. Photoreactivity of Thiophene-Based Core@Shell Nanoparticles: The Effect of Photoinduced Charge Separation on In VivoROS Production

Author

Zangoli, Mattia, Cantelli, Andrea, Candini, Andrea, Lewinska, Anna, Fardella, Federica, Tino, Angela, Tommasini, Giuseppina, Wnuk, Maciej, Moschetta, Matteo, Perotto, Sara, Lucarini, Marco, Tortiglione, Claudia, Lanzani, Guglielmo, and Di Maria, Francesca

Abstract

Here, we show that in thiophene-based core@shell nanoparticles, namely, P3HT@PTDO NPs, the nanosegregation of the materials results in a peculiar photoreactivity, which, together with their soft and biocompatible nature, makes them interesting bioplatforms. By combining macroscopic and microscopic Kelvin probe measurements, we show that the surface of core@shell NPs becomes rich in negative charges under light illumination─due to the promotion of photogenerated electrons from the inner P3HT core to the outer oxidized PTDO shell─making them more reactive to the environment (air dopants, water, substrate, etc.). Fluorometric and electron paramagnetic resonance (EPR) techniques revealed the formation of transient reactive oxygen species (ROS) upon illumination of aqueous suspensions of NPs, indicating their photoredox reactivity. Detailed analysis permitted to reveal a type I mechanism in ROS generation, ruling out the formation of potentially biodamaging singlet oxygen species. Finally, the biocompatibility of these systems was tested in cells and Hydra polyps. Core@shell NPs exhibit perfect viability and allow the modulation of ROS generation depending on the shell’s oxygenation degree, both in vitroand in vivo, in agreement with EPR measurements.

Published
2023
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28. Push–pull thiophene-based small molecules with donor and acceptor units of varying strength for photovoltaic application: beyond P3HT and PCBM

Author

Marinelli, Martina, primary, Candini, Andrea, additional, Monti, Filippo, additional, Boschi, Alex, additional, Zangoli, Mattia, additional, Salatelli, Elisabetta, additional, Pierini, Filippo, additional, Lanzi, Massimiliano, additional, Zanelli, Alberto, additional, Gazzano, Massimo, additional, and Di Maria, Francesca, additional

Published
2021
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30. Low temperature magnetic properties and spin dynamics in single crystals of Cr8Zn antiferromagnetic molecular rings.

Author

Adelnia, Fatemeh, Chiesa, Alessandro, Bordignon, Sara, Carretta, Stefano, Ghirri, Alberto, Candini, Andrea, Cervetti, Christian, Evangelisti, Marco, Affronte, Marco, Sheikin, Ilya, Winpenny, Richard, Timco, Grigore, Borsa, Ferdinando, and Lascialfari, Alessandro

Subjects
LOW temperatures, MAGNETIC properties, SINGLE crystals, ANTIFERROMAGNETIC materials, ENERGY levels (Quantum mechanics), THERMODYNAMICS
Abstract

A detailed experimental investigation of the effects giving rise to the magnetic energy level structure in the vicinity of the level crossing (LC) at low temperature is reported for the open antiferromagnetic molecular ring Cr8Zn. The study is conducted by means of thermodynamic techniques (torque magnetometry, magnetization and specific heat measurements) and microscopic techniques (nuclear magnetic resonance line width, nuclear spin lattice, and spin-spin relaxation measurements). The experimental results are shown to be in excellent agreement with theoretical calculations based on a minimal spin model Hamiltonian, which includes a Dzyaloshinskii-Moriya interaction. The first ground state level crossing at μ0Hc1 = 2.15 T is found to be an almost true LC while the second LC at μ0Hc2 = 6.95 T has an anti-crossing gap of Δ12 = 0.19 K. In addition, both NMR and specific heat measurements show the presence of a level anti-crossing between excited states at μ0H = 4.5 T as predicted by the theory. In all cases, the fit of the experimental data is improved by introducing a distribution of the isotropic exchange couplings (J), i.e., using a J strain model. The peaks at the first and second LCs in the nuclear spin-lattice relaxation rate are dominated by inelastic scattering and a value of Γ ~ 1010 rad/s is inferred for the life time broadening of the excited state of the open ring, due to spin phonon interaction. A loss of NMR signal (wipe-out effect) is observed for the first time at LC and is explained by the enhancement of the spin-spin relaxation rate due to the inelastic scattering. [ABSTRACT FROM AUTHOR]

Published
2015
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32. Dispersion Stability and Surface Morphology Study of Electrochemically Exfoliated Bilayer Graphene Oxide

Author

Xia, Zhenyuan, primary, Maccaferri, Giulio, additional, Zanardi, Chiara, additional, Christian, Meganne, additional, Ortolani, Luca, additional, Morandi, Vittorio, additional, Bellani, Vittorio, additional, Kovtun, Alessandro, additional, Dell’Elce, Simone, additional, Candini, Andrea, additional, Liscio, Andrea, additional, and Palermo, Vincenzo, additional

Published
2019
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33. Structure-dependent electrical properties of graphene nanoribbon devices with graphene electrodes

Author

Martini, Leonardo, primary, Chen, Zongping, additional, Mishra, Neeraj, additional, Barin, Gabriela Borin, additional, Fantuzzi, Paolo, additional, Ruffieux, Pascal, additional, Fasel, Roman, additional, Feng, Xinliang, additional, Narita, Akimitsu, additional, Coletti, Camilla, additional, Müllen, Klaus, additional, and Candini, Andrea, additional

Published
2019
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35. The ultrafast dynamics and conductivity of photoexcited graphene at different Fermi energies

Author

Tomadin, Andrea, Hornett, Sam M., Wang, Hai I., Alexeev, Evgeny M., Candini, Andrea, Coletti, Camilla, Turchinovich, Dmitry, Kläui, Mathias, Bonn, Mischa, Koppens, Frank H. L., Hendry, Euan, Polini, Marco, Tielrooij, Klaas-Jan, Tomadin, Andrea, Hornett, Sam M., Wang, Hai I., Alexeev, Evgeny M., Candini, Andrea, Coletti, Camilla, Turchinovich, Dmitry, Kläui, Mathias, Bonn, Mischa, Koppens, Frank H. L., Hendry, Euan, Polini, Marco, and Tielrooij, Klaas-Jan

Abstract

For many of the envisioned optoelectronic applications of graphene, it is crucial to understand the subpicosecond carrier dynamics immediately following photoexcitation and the effect of photoexcitation on the electrical conductivity—the photoconductivity. Whereas these topics have been studied using various ultrafast experiments and theoretical approaches, controversial and incomplete explanations concerning the sign of the photoconductivity, the occurrence and significance of the creation of additional electron-hole pairs, and, in particular, how the relevant processes depend on Fermi energy have been put forward. We present a unified and intuitive physical picture of the ultrafast carrier dynamics and the photoconductivity, combining optical pump–terahertz probe measurements on a gate-tunable graphene device, with numerical calculations using the Boltzmann equation. We distinguish two types of ultrafast photo-induced carrier heating processes: At low (equilibrium) Fermi energy (EF ≲ 0.1 eV for our experiments), broadening of the carrier distribution involves interband transitions (interband heating). At higher Fermi energy (EF ≳ 0.15 eV), broadening of the carrier distribution involves intraband transitions (intraband heating). Under certain conditions, additional electron-hole pairs can be created [carrier multiplication (CM)] for low EF, and hot carriers (hot-CM) for higher EF. The resultant photoconductivity is positive (negative) for low (high) EF, which in our physical picture, is explained using solely electronic effects: It follows from the effect of the heated carrier distributions on the screening of impurities, consistent with the DC conductivity being mostly due to impurity scattering. The importance of these insights is highlighted by a discussion of the implications for graphene photodetector applications.

Published
2018

36. The ultrafast dynamics and conductivity of photoexcited graphene at different Fermi energies

Author

Tomadin, Andrea, primary, Hornett, Sam M., additional, Wang, Hai I., additional, Alexeev, Evgeny M., additional, Candini, Andrea, additional, Coletti, Camilla, additional, Turchinovich, Dmitry, additional, Kläui, Mathias, additional, Bonn, Mischa, additional, Koppens, Frank H. L., additional, Hendry, Euan, additional, Polini, Marco, additional, and Tielrooij, Klaas-Jan, additional

Published
2018
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39. Synthesis of Graphene Nanoribbons by Ambient-Pressure Chemical Vapor Deposition and Device Integration

Author

Chen, Zongping, primary, Zhang, Wen, additional, Palma, Carlos-Andres, additional, Lodi Rizzini, Alberto, additional, Liu, Bilu, additional, Abbas, Ahmad, additional, Richter, Nils, additional, Martini, Leonardo, additional, Wang, Xiao-Ye, additional, Cavani, Nicola, additional, Lu, Hao, additional, Mishra, Neeraj, additional, Coletti, Camilla, additional, Berger, Reinhard, additional, Klappenberger, Florian, additional, Kläui, Mathias, additional, Candini, Andrea, additional, Affronte, Marco, additional, Zhou, Chongwu, additional, De Renzi, Valentina, additional, del Pennino, Umberto, additional, Barth, Johannes V., additional, Räder, Hans Joachim, additional, Narita, Akimitsu, additional, Feng, Xinliang, additional, and Müllen, Klaus, additional

Published
2016
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40. Relay-Like Exchange Mechanism through a Spin Radical between TbPc2 Molecules and Graphene/Ni(111) Substrates

Author

Marocchi, Simone, primary, Candini, Andrea, additional, Klar, David, additional, Van den Heuvel, Willem, additional, Huang, Haibei, additional, Troiani, Filippo, additional, Corradini, Valdis, additional, Biagi, Roberto, additional, De Renzi, Valentina, additional, Klyatskaya, Svetlana, additional, Kummer, Kurt, additional, Brookes, Nicholas B., additional, Ruben, Mario, additional, Wende, Heiko, additional, del Pennino, Umberto, additional, Soncini, Alessandro, additional, Affronte, Marco, additional, and Bellini, Valerio, additional

Published
2016
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42. Low temperature magnetic properties and spin dynamics in single crystals of Cr8Zn antiferromagnetic molecular rings

Author

Adelnia, Fatemeh, primary, Chiesa, Alessandro, additional, Bordignon, Sara, additional, Carretta, Stefano, additional, Ghirri, Alberto, additional, Candini, Andrea, additional, Cervetti, Christian, additional, Evangelisti, Marco, additional, Affronte, Marco, additional, Sheikin, Ilya, additional, Winpenny, Richard, additional, Timco, Grigore, additional, Borsa, Ferdinando, additional, and Lascialfari, Alessandro, additional

Published
2015
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44. Magnetic interplay between two different lanthanides in a tris-phthalocyaninato complex: a viable synthetic route and detailed investigation in the bulk and on the surface

Author

Lan, Yanhua, primary, Klyatskaya, Svetlana, additional, Ruben, Mario, additional, Fuhr, Olaf, additional, Wernsdorfer, Wolfgang, additional, Candini, Andrea, additional, Corradini, Valdis, additional, Lodi Rizzini, Alberto, additional, del Pennino, Umberto, additional, Troiani, Filippo, additional, Joly, Loïc, additional, Klar, David, additional, Wende, Heiko, additional, and Affronte, Marco, additional

Published
2015
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46. Ferromagnetic Exchange Coupling between Fe Phthalocyanine and Ni(111) Surface Mediated by the Extended States of Graphene

Author

Candini, Andrea, primary, Bellini, Valerio, additional, Klar, David, additional, Corradini, Valdis, additional, Biagi, Roberto, additional, De Renzi, Valentina, additional, Kummer, Kurt, additional, Brookes, Nicholas B., additional, del Pennino, Umberto, additional, Wende, Heiko, additional, and Affronte, Marco, additional

Published
2014
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47. Surface Investigation on Gd4M8(M = Zn, Ni) Single Molecule Coolers

Author

Corradini, Valdis, primary, Ghirri, Alberto, additional, Candini, Andrea, additional, Biagi, Roberto, additional, del Pennino, Umberto, additional, De Renzi, Valentina, additional, Dotti, Gianluca, additional, Otero, Edwige, additional, Hooper, Thomas N., additional, Inglis, Ross, additional, Brechin, Euan K., additional, and Affronte, Marco, additional

Published
2014
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49. Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films

Author

Klar, David, primary, Klyatskaya, Svetlana, additional, Candini, Andrea, additional, Krumme, Bernhard, additional, Kummer, Kurt, additional, Ohresser, Philippe, additional, Corradini, Valdis, additional, de Renzi, Valentina, additional, Biagi, Roberto, additional, Joly, Loic, additional, Kappler, Jean-Paul, additional, del Pennino, Umberto, additional, Affronte, Marco, additional, Wende, Heiko, additional, and Ruben, Mario, additional

Published
2013
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