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Excitonic quantum oscillations are observed in correlated electron–hole bilayers and quantum phase transitions are identified between excitonic insulator and bilayer quantum Hall states under strong magnetic fields.

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.

Detection of electric fields, central to chemical and biological processes, has been limited to measurements of current (e.g., electrodes) and secondary reporters (e.g., fluorescent dyes). Here, the authors demonstrate an optical platform capable of imaging electric field dynamics with high spatio-temporal resolution.

The interplay between reduced dimensionality and interactions in monolayer transition metal dichalcogenides has been of great research interest. Here the authors report an insulating dimer ground state in 1T-IrTe₂, driven by the combined effect of the charge density wave instability and local atomic bond formation.

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.

Tomonaga-Luttinger liquid behavior has been observed within 1D defects in transition metal dichalcogenides. Here, using complementary experiments and engineered defects, the authors demonstrate the importance of graphene as a substrate and its role in the formation of this quasiparticle excitation in 2D WS₂.

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.

Bottom-up fabrication of GNR heterojunctions exhibiting atomically perfect heterojunction interfaces can be obtained from a single molecular precursor via post-growth modification

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.

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.

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

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.

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.

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

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.

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.

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

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.

The electrons that contribute to the Mott insulator state in single-layer 1T-TaSe2 are shown to also have a rich variation in their orbital occupation. As more layers are added, both the insulating state and orbital texture weaken.

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.

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.

Unconventional quasiparticles carrying spin but not electric charge emerge in quantum spin liquid phases. The Kondo interaction of these spinon quasiparticles with magnetic impurities may now have been observed.

Some quantum spin liquids are expected to have an effective Fermi surface of fractionalized spinon excitations. The two-dimensional spin liquid candidate 1T-TaSe₂ has charge density modulations that may be caused by an unstable spinon Fermi surface.

So far, only indirect evidence of Wigner crystals has been reported, but a specially designed scanning tunnelling microscope is used here to directly image them in a moiré heterostructure.

Stabilizing non-trivial magnetic spin textures at room temperature remains challenging. Here, the authors propose introducing magnetic atoms into the van der Waals gap of 2D magnets Fe₃GaTe₂ to stabilize the magnetic spin textures beyond skyrmion.

Transition metal dichalcogenides may host exotic topological phases in the two-dimensional limit, but detailed atomic properties have rarely been explored. Here, Ugeda et al. observe edge-states at the interface between a single layer quantum spin Hall insulator 1T′-WSe₂ and a semiconductor 1H-WSe₂.

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

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 single-bond-resolved chemical structures of transient intermediates in a complex bimolecular reaction cascade were imaged by noncontact atomic force microscopy. Theoretical simulations reveal that the kinetic stabilization of experimentally observable intermediates is governed by selective energy dissipation to the substrate and entropic changes along the reaction pathway.

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

In an application of terahertz phonon engineering, terahertz phonons were generated, detected and manipulated through precise integration of atomically thin layers in van der Waals heterostructures.

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.

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.

A combination of photoemission and scanning tunnelling spectroscopy measurements provide compelling evidence that single layers of 1T'-WTe₂ are a class of quantum spin Hall insulator.

Transition metal dichalcogenides are attracting widespread attention for their appealing optoelectronic properties. Using a combination of numerical and experimental techniques, the exciton binding energy is now determined for MoSe₂ on graphene.

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.

2D surface plasmon polaritons are used to probe the domain-wall solitons in bilayer graphene; near-field infrared nanoscopy reveals various domain-wall structures in mechanically exfoliated 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.

A scanning tunnelling microscopy study demonstrates that one-dimensional charge density waves can form at twin boundaries in a monolayer transition metal dichalcogenide.

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.

Width-modulated heterostructures are created in graphene nanoribbons using a bottom-up approach, thus achieving molecular-scale bandgap engineering.