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One-dimensional molecular arrays on graphene field-effect transistors can be reversibly switched between different periodic charge states by tuning the graphene Fermi level via a back-gate electrode and by manipulating individual molecules, allowing them to function as a nanoscale shift register.

Understanding of electrolyte-electrode interfaces is limited due to the lack of suitable probing techniques. Here, the authors present a vibrational spectroscopy based on graphene gratings, which enables sensitive and interface-specific detection of molecular vibrations at electrolyte-electrode interfaces.

Interlayer coupling between two-dimensional materials is known to result in interesting physical properties. Here, the authors study the effect of a twist angle between two-dimensional molybdenum disulphide on interlayer coupling, observing an indirect bandgap, the size of which depends on the twist angle.

Double-walled carbon nanotubes are a convenient system for studying quantum mechanical interactions in distinct but coupled nanostructures. Liu et al.characterize the coupling between radial-breathing mode oscillations of inner and outer walls of many double-walled nanotubes of different diameter and chirality.

Two laser beams with different energies and configurations can be used to reversibly dope graphene via chlorination and chlorine removal, allowing rewritable graphene photodetectors to be fabricated.

An electron beam technique can be used to write high-resolution doping patterns in graphene and MoS₂ van der Waals heterostructures, and could allow doped circuit designs to be created.

What happens to correlated electronic phases—superconductivity and charge density wave ordering—as a material is thinned? Experiments show that both can remain intact in just a single layer of niobium diselenide.

Graphene nanoribbons show promise for high-performance field-effect transistors, however they often suffer from short lengths and wide band gaps. Here, the authors use a bottom-up synthesis approach to fabricate 9- and 13-atom wide ribbons, enabling short-channel transistors with 10⁵ on-off current ratio.

Colour centre emission from hexagonal boron nitride (hBN) holds promise for quantum technologies but activation and tuning are challenging. Here, the authors show twist-angle emission brightness tuning and external voltage brightness modulation at the twisted interface of hBN flakes.

Moiré superlattices offer a tunable platform for studying charge and spin phenomena in correlated solid-state systems. Here, the authors explore spin transport in twisted WSe₂/WS₂ superlattices and find signatures of spin–charge transport decoupling.

Scanning tunnelling spectroscopy and ab initio simulations reveal buckling reconstruction and in-plane strain redistribution in WSe₂/WS₂ moiré heterostructures.

The local electronic structure of interface states between topologically distinct domains is imaged and controlled, allowing visualization of the interplay between strong interactions and non-trivial topology.

Due to the crystal symmetry of single-layer transition metal dichalcogenides and the fact that the conduction and valence band edges are at the zone-edge K points, the 2p exciton states are split. A two-colour pump–probe scheme is used to drive the 1s–2p exciton transition, and then probe the changes in absorption near the spectral position of the 1s line to measure the splitting energy.

Moiré superlattice exciton states are observed in WSe₂/WS₂ heterostructures with closely aligned layers.

The flat electronic bands that are associated with ordered phases in twisted bilayer graphene at a magic twist angle have been imaged using angle-resolved photoemission spectroscopy.

Stacked 2D materials can host excitons with distinct valley selection rules due to the spatial variation of the moiré pattern. The authors demonstrate this via optical spectroscopy, opening a route for control of optoelectronic devices.

In metals, the Coulomb potential of charged impurities is strongly screened, but in graphene, the potential charge of a few-atom cluster of cobalt can extend up to 10 nm. By measuring differences in the way electron-like and hole-like Dirac fermions are scattered from this potential, the intrinsic dielectric constant of graphene can be determined.

Inelastic light scattering spectroscopy is a powerful tool in materials science to probe elementary excitations. In a quantum-mechanical picture, these excitations are generated by the incident photons via intermediate electronic transitions. It is now shown that it is possible to manipulate these intermediate 'quantum pathways' using electrostatically doped graphene. A surprising effect is revealed where blocking one pathway results in an increased intensity, unveiling a mechanism of destructive quantum interference between different Raman pathways. The study refines understanding of Raman scattering in graphene and indicates the possibility of controlling quantum pathways to produce unusual inelastic light scattering phenomena.

The results of simultaneous measurements of the structure and optical properties of more than 200 single-walled carbon nanotubes are reported and included in an atlas that allows the chiral index of any single-walled nanotube to be determined from a measurement of its optical resonances, and vice versa.

A new hybrid phonon–exciton excited state in bilayer graphene can be tuned electrically, with possible application to phonon lasers.

Graphene microribbons behave as tunable metamaterials at terahertz frequencies.

A high-throughput optical imaging and spectroscopy technique has now been developed that characterizes the chirality and electronic structure of individual single-walled carbon nanotubes either on their growth substrate or in functional devices.

Edge effects matter in graphene, particularly in nanoribbons. A study using scanning tunnelling microscopy and spectroscopy reveals how chirality at the atomically well-defined edges of a graphene nanoribbon affects its electronic structure.

By varying the voltage on an isolated gate electrode beneath a graphene sheet, the ionization state of cobalt atoms on its surface can be controlled. This enables the electronic structure of individual ionized atoms, and the resulting cloud of screening electrons that form around them, to be obtained with a scanning tunnelling microscope.

The ability to electrically control the bandgap, a fundamental property of semiconductors and insulators that determines electrical and optical response, is highly desirable for device design and functionality. Experiments now demonstrate versatile control of the bandgap in bilayer graphene-based devices by use of electric fields.

The emergence of optically silent phonons show that strong interlayer electron–phonon coupling can arise in van der Waals heterostructures, with the vibrational modes in one layer coupling to the electronic states in a neighbouring layer.

Two concentric carbon nanotubes don’t need to have a common finite unit cell. Absorption spectra of such incommensurate double-walled carbon nanotubes reveal strong hybridization of the electron wavefunctions — unusual for van der Waals-coupled structures. The observations can be rationalized by zone folding the electronic structure of twisted-and-stretched graphene bilayers.

One of the many unusual characteristics of graphene is that it shows ‘puddles’ of positive and negative charge throughout. A systematic scanning tunnelling microscope study shows that these puddles are not a consequence of ripples in graphene’s structure as originally thought, but are due to charged impurities below its surface.

The scanning tunnelling microscope can be used to image and manipulate individual defects in bulk insulating hexagonal boron nitride by capping the material with a monolayer of graphene.

Relativistic Dirac fermions can be locally confined in nanoscale graphene quantum dots using electrostatic gating, and directly imaged using scanning tunnelling microscopy before escaping via Klein tunnelling.

Inorganic nanowires composed of gold(I) cyanide can be grown directly on pristine graphene, aligning themselves with the zigzag lattice directions of the graphene, and then used as templates to create graphene nanoribbons with zigzag-edged directions.

Scanning tunnelling spectra of a graphene field-effect transistor reveal an unexpected tenfold increase in conductance as a result of phonon-mediated inelastic tunnelling.

The use of monolayers of hexagonal boron nitride as the cationic diffusion barrier and graphene aerogel mixed with spiro-OMeTAD as the hole transport layer allows the fabrication of graded bandgap perovskite solar cells with high efficiency.

Layer-stacking domain walls in van der Waals heterostructures form a broadly tunable Luttinger liquid system, including both isolated and coupled arrays.

The authors use scanning tunnelling microscopy and spectroscopy to visualize the electronic structure of mirror twin boundaries, revealing a Tomonaga–Luttinger liquid.

Nanopore engineering holds great promise for energy, DNA sequencing, and quantum information technologies, but pore evolution, particularly in presumably stable materials such as boron nitride, is largely unexplored. Here, the authors use high-resolution transmission electron microscopy to show that different nanopores formed in mono- and multi-layer hexagonal boron nitride are stable in vacuum but undergo dramatic changes in air.

A novel scanning single-electron charging spectroscopy enables nanometre-scale imaging of quasiparticle excitations and thermodynamic gaps in generalized Wigner crystals.

The authors combine laser excitation and scanning tunnelling spectroscopy to visualize the electron and hole distributions in photoexcited moiré excitons in twisted bilayer WS₂. This photocurrent tunnelling microscopy approach enables the study of photoexcited non-equilibrium moiré phenomena at atomic scales.

Transmission electron microscopy is essential for three-dimensional atomic structure determination, but solving complex heterogeneous structures containing light elements remains challenging. Here, authors solve a complex nanostructure using atomic resolution ptychographic electron tomography.

Placement of charge centres with atomic precision on graphene allows exploration of new types of confinement of charge carriers. Here, the authors fabricate atomically precise arrays of point charges on graphene and observe the onset of a frustrated supercritical regime.

Recent electron microscopy techniques have attracted significant attention for their ability to image electric fields at the atomic level. Here, the authors investigate the possibility to separate the charge density contributions of core and valence electrons in monolayer MoS2, highlighting the limitations induced by the electron probe shape.

By using new on-chip terahertz spectroscopy techniques to measure the absorption spectra of a graphene microribbon as well as the energy waves close to charge neutrality, hydrodynamic collective excitations are observed.

Twisted moiré heterostructures offer a highly tunable solid-state platform for exploring fundamental condensed matter physics. Here, the authors use scanning tunnelling microscopy to investigate the local electronic structure of the gate-controlled quantum anomalous Hall insulator state in twisted monolayer–bilayer graphene.

The development of single-molecule electronics calls for precise tuning of the electronic properties of individual molecules that go beyond two-terminal control. Here, Wickenburg et al. show gate-tunable switch of charge states of an isolated molecule using a graphene-based field-effect transistor.

When independent layers of electrons and holes are in close proximity to each other, their Coulomb interaction allows them to pair into neutral bosons and form an insulating state. This phenomenon is reported in a heterostructure of 2D materials.