Graphene

  • Article
    | Open Access

    Graphene nanoribbons are potential systems for engineering topological phases of matter, but the pre-required gapped phases are difficult to find. Here, the authors show that chiral graphene nanoribbons undergo a transition from metallic to topological insulators, and then to trivial band insulators as they are narrowed down to nanometer widths.

    • Jingcheng Li
    • , Sofia Sanz
    •  & Jose Ignacio Pascual
  • Article
    | Open Access

    Magic-angle twisted bilayer graphene exhibits a quantum anomalous Hall effect at 3/4 filling; however, its mechanism is debated. Here, the authors show that such a phase can be realized in a lattice model of twisted bilayer graphene in the strong coupling limit, and interpret the results in terms of a topological Mott insulator phase.

    • Bin-Bin Chen
    • , Yuan Da Liao
    •  & Zi Yang Meng
  • Article
    | Open Access

    Understanding the interaction between spin and valley degrees of freedom in graphene-based quantum dots underpins their applications in electronics and quantum information. Here, the authors study the low-energy spectrum and resolve the spin-valley coupling in single-electron quantum dots in bilayer graphene.

    • L. Banszerus
    • , S. Möller
    •  & C. Stampfer
  • Article
    | Open Access

    The effect of strain-induced pseudo-magnetic fields on the optical properties of graphene has not been experimentally explored yet. Here, pseudo-magnetic fields reaching values of 100 T are shown to increase by more than an order of magnitude the relaxation lifetime of hot carriers in periodically strained graphene.

    • Dong-Ho Kang
    • , Hao Sun
    •  & Donguk Nam
  • Article
    | Open Access

    Here, the authors investigate the long-range interaction and coalescence mechanism of water and ethanol nanopockets encapsulated in twisted bilayer graphene, showing the complete recovery of moiré patterns after the motion of the contaminants.

    • Yuan Hou
    • , Zhaohe Dai
    •  & Zhong Zhang
  • Article
    | Open Access

    Graphene-based photodetectors have many advantages for applications. Here, the authors demonstrate a high-speed optical coherent receiver for optical communications based on graphene-on-plasmonic slot waveguide photodetectors.

    • Yilun Wang
    • , Xiang Li
    •  & Xinliang Zhang
  • Article
    | Open Access

    Graphene is the archetype for realizing two-dimensional topological phases of matter. Here, the authors introduce a new topological classification connected to polarization transport, where the topological number is revealed in the spatiotemporal dispersion of the susceptibility tensor.

    • Todd Van Mechelen
    • , Wenbo Sun
    •  & Zubin Jacob
  • Article
    | Open Access

    The properties of graphene/polymer composites are usually limited by the use of discontinuous graphene flakes. Here, the authors report a fabrication method to realise continuous cm-scale graphene/polymer nanolaminates with enhanced electromagnetic interference shielding effectiveness, conductivity and mechanical properties.

    • Christos Pavlou
    • , Maria Giovanna Pastore Carbone
    •  & Costas Galiotis
  • Article
    | Open Access

    The integration of nano-molecules into microelectronic circuitry is challenging. Here, the authors provide a scalable method for contacting a self-assembled monolayer of nanoparticles with a single layer of graphene that produces single-electron effects, in the form of a Coulomb staircase, with a yield of at least 70%.

    • Joel M. Fruhman
    • , Hippolyte P.A.G. Astier
    •  & Christopher J. B. Ford
  • Article
    | Open Access

    It was suggested that the breakdown of the quantum Hall effect in graphene originates from the coupling between counter propagating edge modes. Here, by using scanning gate microscopy, the authors propose a microscopic mechanism of this coupling due to antidots present at graphene edges.

    • N. Moreau
    • , B. Brun
    •  & B. Hackens
  • Review Article
    | Open Access

    This review presents an overview of scenarios where van der Waals (vdW) materials provide unique advantages for nanophotonic biosensing applications. The authors discuss basic sensing principles based on vdW materials, advantages of the reduced dimensionality as well as technological challenges.

    • Sang-Hyun Oh
    • , Hatice Altug
    •  & Michael S. Strano
  • Article
    | Open Access

    Optical receivers based on graphene still suffer from low responsivity. Here, the authors integrate a photo-thermoelectric graphene photodetector with a Si micro-ring resonator, and obtain a voltage responsivity ~ 90 V/W and a reduction of energy-per-bit consumption, enabling performance on par with mature semiconductor technology.

    • S. Schuler
    • , J. E. Muench
    •  & T. Mueller
  • Article
    | Open Access

    Knowledge of the quantum response of materials is essential for designing light–matter interactions at the nanoscale. Here, the authors report a theory for understanding the impact of metallic quantum response on acoustic graphene plasmons and how such response could be inferred from measurements.

    • P. A. D. Gonçalves
    • , Thomas Christensen
    •  & N. Asger Mortensen
  • Article
    | Open Access

    Flow through nanometer scale channels facilitates an unmasked study of water-surface molecular interactions. Here, Keerthi et al. show with conduits made from graphite and hexagonal boron nitride that strong hydrophobicity does not rule out enhanced stickiness and friction.

    • Ashok Keerthi
    • , Solleti Goutham
    •  & Boya Radha
  • Article
    | Open Access

    The dynamics of water molecules at interfaces controls natural and artificial processes, but experimental investigations have been challenging. Here the authors investigate water molecules on a graphene surface using helium spin-echo spectroscopy, and reveal a regime where freely mobile molecules undergo strong repulsive mutual interactions which inhibit ice nucleation.

    • Anton Tamtögl
    • , Emanuel Bahn
    •  & William Allison
  • Article
    | Open Access

    The broken-symmetry edge states that are the hallmark of the quantum Hall effect in graphene have eluded spatial measurements. Here, the authors spatially map the quantum Hall broken-symmetry edge states using atomic force microscopy and show a gapped ground state proceeding from the bulk through to the quantum Hall edge boundary.

    • Sungmin Kim
    • , Johannes Schwenk
    •  & Joseph A. Stroscio
  • Article
    | Open Access

    Nanographenes are emerging as a distinctive class of functional materials for electronic and optical devices. Here, the authors develop a facile strategy to recompose helicenes into a variety of chiral nanographenes through an oxidative cyclo-rearrangement reaction.

    • Chengshuo Shen
    • , Guoli Zhang
    •  & Huibin Qiu
  • Article
    | Open Access

    The development of a quantitative and predictive theory of quantum light-matter interactions in ultrathin materials is both a conceptual and computational challenge. Here, the authors develop such a framework by combining density functional theory with macroscopic quantum electrodynamics, and use it to quantify the Purcell effect in van der Waals heterostructures.

    • Mark Kamper Svendsen
    • , Yaniv Kurman
    •  & Kristian S. Thygesen
  • Article
    | Open Access

    Here, the authors report optoelectronic mixing up to 67 GHz using high-frequency back-gated graphene field effect transistors (GFETs). These devices mix an electrical signal injected into the GFET gate and a modulated optical signal onto a single layer graphene channel.

    • A. Montanaro
    • , W. Wei
    •  & E. Pallecchi
  • Article
    | Open Access

    Twisted double bilayer graphene hosts flat bands that can be tuned with an electric field. Here, by using gate-tuned scanning tunneling spectroscopy, the authors demonstrate the tunability of the flat band and reveal spectral signatures of correlated electron states and the topological nature of the flat band.

    • Xiaomeng Liu
    • , Cheng-Li Chiu
    •  & Ali Yazdani
  • Article
    | Open Access

    Twisted double bilayer graphene is a novel van der Waals system that hosts an electric-field-tunable correlated state at half-filling. Here the authors reveal the delocalized nature of this state by scanning tunnelling microscopy and spectroscopy, suggesting an underlying mechanism of symmetry breaking driven by non-local exchange.

    • Canxun Zhang
    • , Tiancong Zhu
    •  & Michael F. Crommie
  • Article
    | Open Access

    Transparent photodetectors based on graphene stacked vertically along the optical axis have shown promising potential for light field reconstruction. Here, the authors develop transparent photodetector arrays and implement a neural network for real-time 3D optical imaging and object tracking.

    • Dehui Zhang
    • , Zhen Xu
    •  & Theodore B. Norris
  • Article
    | Open Access

    Li-ion battery electrodes contain inactive materials, such as conducting agents and polymeric binders, which limit the energy density. Here, the authors demonstrate highly dense Ni-rich cathodes with improved volumetric capacities by coating graphene and minimizing the inactive components.

    • Chang Won Park
    • , Jung-Hun Lee
    •  & Young-Jun Kim
  • Article
    | Open Access

    Here, the authors use scanning probe photocurrent imaging to resolve nanoscale variations of the Seebeck coefficient occurring at domain walls separating micron-scale AB and BA stacking regions in twisted bilayer graphene, and observe hyperbolic enhancement of the photocurrent pattern.

    • S. S. Sunku
    • , D. Halbertal
    •  & D. N. Basov
  • Article
    | Open Access

    Here, the authors use a nanoscale probe to study the photoresponse within a single moiré unit cell of minimally twisted bilayer graphene, and observe an intricate photo-thermoelectric response attributed to the Seebeck coefficient variation at AB-BA domain boundaries.

    • Niels C. H. Hesp
    • , Iacopo Torre
    •  & Frank H. L. Koppens
  • Article
    | Open Access

    Acoustic graphene plasmons are superior to the graphene surface plasmons in field confinement and normalized propagation length, thus promising for applications. Here, the authors report near-field imaging of acoustic plasmons in high-quality CVD graphene, measure the AGP dispersion and propagation loss, and investigate their behavior in a periodic structure.

    • Sergey G. Menabde
    • , In-Ho Lee
    •  & Min Seok Jang
  • Article
    | Open Access

    Nonlinear dissipation is frequently observed in nanomechanical resonators, but its microscopic origin remains unclear. Here, nonlinear damping is found to be enhanced in graphene nanodrums close to internal resonance conditions, providing insights on the mechanisms at the basis of this phenomenon.

    • Ata Keşkekler
    • , Oriel Shoshani
    •  & Farbod Alijani
  • Article
    | Open Access

    In field-effect transistors, a semiconducting channel is indispensable for device switching. Here, the authors demonstrate semiconductor-less switching via modulation of the field emission barrier height across a graphene-hBN interface with ON/OFF ratio of 106.

    • Jun-Ho Lee
    • , Dong Hoon Shin
    •  & Hyun-Jong Chung
  • Article
    | Open Access

    Covalently 2D-patterning graphene with different chemical functionalities is an attractive way to tailor its physical and chemical properties. Here, the authors realize spatially defined 2D-hetereoarchitectures of graphene via a strategy of molecular embroidering.

    • Tao Wei
    • , Malte Kohring
    •  & Andreas Hirsch
  • Article
    | Open Access

    Vertically stacked graphene oxide sheets are promising structures for molecular sieving technologies. By folding large planar sheets in an accordion-like manner, Liu et al. fabricate a thin robust filter with near-vertically aligned nanochannels geared towards commercial separation membranes.

    • Muchun Liu
    • , Paula J. Weston
    •  & Robert H. Hurt
  • Article
    | Open Access

    Merons are a type of topological spin texture, with relevance for both fundamental and technological problems. In this theoretical work, Augustin et al. show that the van der Waals ferromagnetic CrCl3 can host merons and anti-merons, and explore the dynamics and interactions of these quasi-particles.

    • Mathias Augustin
    • , Sarah Jenkins
    •  & Elton J. G. Santos
  • Article
    | Open Access

    Thermoelectricity due to the interplay of the nonlocal Cooper pair splitting and the elastic co-tunneling in normal metal-superconductor-normal metal structure is predicted. Here, the authors observe the non-local Seebeck effect in a graphene-based Cooper pair splitting device.

    • Z. B. Tan
    • , A. Laitinen
    •  & P. J. Hakonen
  • Article
    | Open Access

    Graphene-covering technology provides a promising approach for achieving a non-noble-metal-catalyst with corrosion protection and catalytic activity under acidic media. Here, the authors unveil that the electrochemical hydrogen evolution mechanism is governed by the proton penetration phenomenon.

    • Kailong Hu
    • , Tatsuhiko Ohto
    •  & Yoshikazu Ito
  • Article
    | Open Access

    Nanocomposite (NC) printing emerged as a major approach to translate nanomaterial properties to 3D geometries but printing of conventional NCs lacks control over nanomaterial connection. Here, the authors develop viscoelastic Pickering emulgels as NC inks through jamming nanomaterials on interfaces and in continuous phase

    • Yuanyuan Zhang
    • , Guangming Zhu
    •  & Feng Xing
  • Article
    | Open Access

    Atomically thin porous graphene is promising for filtration and sieving applications. Here the authors, using a laser-actuated micro-drum device of bilayer graphene with controlled number of nanopores, and measuring the permeation rate of different gases, show that it can also be used for permeation-based sensing.

    • I. E. Rosłoń
    • , R. J. Dolleman
    •  & P. G. Steeneken
  • Article
    | Open Access

    Spontaneous symmetry breaking of flat bands in twisted graphene systems may lead to anomalous Hall effect with a precursor state which has not been observed. Here, the authors probe this precursor state by observing bulk valley current and large nonlocal voltage several micrometers away from the charge current path in twisted double bilayer graphene.

    • Subhajit Sinha
    • , Pratap Chandra Adak
    •  & Mandar M. Deshmukh
  • Article
    | Open Access

    Here, the authors use Raman spectroscopy on circular graphene drums to demonstrate dynamical softening of optical phonons induced by the macroscopic flexural motion of graphene, and find evidence that the strain in graphene is enhanced under non-linear driving.

    • Xin Zhang
    • , Kevin Makles
    •  & Stéphane Berciaud
  • Article
    | Open Access

    Designing efficient and low power memristors-based neuromorphic systems remains a challenge. Here, the authors present graphene-based multi-level (>16) and non-volatile memristive synapses with arbitrarily programmable conductance states capable of weight assignment based on k-means clustering.

    • Thomas F. Schranghamer
    • , Aaryan Oberoi
    •  & Saptarshi Das
  • Article
    | Open Access

    Here, the authors explore the blue photoluminescence signal arising from the interface between graphene and h-BN arranged in in-plane heterostructures, and fabricate a blue light emitting device utilizing the heterojunction as the emitting layer.

    • Gwangwoo Kim
    • , Kyung Yeol Ma
    •  & Hyeon Suk Shin
  • Article
    | Open Access

    An orbital magnetic moment emerges as a result of inversion symmetry broken at the graphene/h-BN moiré superlattice. Here, Moriya et al. report thermoelectric evidence of magnetic field induced valley splitting for a van Hove singularity in this superlattice, suggesting the emergence of an orbital magnetic moment.

    • Rai Moriya
    • , Kei Kinoshita
    •  & Tomoki Machida