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Measurements of the chemical potential in a monolayer of WSe₂ using a single electron transistor sensing scheme allows for the exact mapping of the level spacing of Landau levels of monolayer WSe₂ in the conductance and valence bands.

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.

Chorus waves are crucial on radiation belt dynamics in the space of magnetized planets. Here, the authors show that initially excited single-band chorus waves can quickly accelerate medium energy electrons, and divide the anisotropic electrons into low and high energy components, which subsequently excite two-band chorus waves.

Mechanisms for generating spin-polarized currents may be helpful for applications. Now one such mechanism that uses the unusual Landau-level spectrum of WSe₂ under a strong magnetic field is demonstrated.

Understanding collective behaviour is an important aspect of managing the pandemic response. Here the authors show in a large global study that participants that reported identifying more strongly with their nation reported greater engagement in public health behaviours and support for public health policies in the context of the pandemic.

Humanity’s Last Exam, a multi-modal benchmark at the frontier of human knowledge, is designed to be an expert-level closed-ended academic benchmark with broad subject coverage.

Radiation reaction (RR) on particles in strong fields is the subject of intense experimental research, but previous efforts lacked statistical significance due to the extreme regimes required. Here, the authors report a 5σ observation of RR and obtain strong, quantitative evidence favouring quantum models over classical, using an all-optical setup where electrons are accelerated by a laser in a gas jet before colliding with a second, intense pulse.

Scanning tunnelling microscopy is used to reveal a new topological kagome magnet with an intrinsic Chern quantum phase, which shows a distinct Landau fan structure with a large Chern gap.

In Bi₂O₂Se thin films, the local inversion-symmetry breaking in two sectors of the [Bi₂O₂]²⁺ layer yields opposite Rashba spin polarizations, which compensate each other and give rise to the hidden Rashba effect. Hence, the films exhibit only even-integer quantum Hall states, but there is no sign of odd-integer states.

Γ and K valleys in twisted transition metal dichalcogenides have emerged as highly tunable knobs for accessing different correlated electronic states in solid-state devices. Here, the authors tune a Mott-Hubbard state to a charge-transfer insulator state in twisted double-bilayer WSe₂.

Lubricated surfaces are known to display extreme liquid repellency. Such behaviour is now confirmed to be due to the formation of a film between the surface and the repelled liquid, with a thickness profile following the Landau–Levich–Derjaguin law.

Electron–phonon coupling influences the thermal and electronic properties of many solid materials. Zeljkovic et al. now combine Landau level spectroscopy and scanning tunnelling microscopy to extract quantitative information on electron–phonon coupling in the insulator lead selenide.

Alfvén waves are fundamental plasma modes that provide a mechanism for the transfer of energy between particles and fields. Here the authors confirm experimentally the conservative energy exchange between Alfvén wave fields and plasma particles via high-resolution MMS observations of Earth’s magnetosphere.

A state that breaks time-reversal symmetry is observed in the normal phase above the superconducting critical temperature in a multiband superconductor. This could be explained by correlations between the Cooper pairs formed in different bands.

Symmetry-breaking distortion on the surface of topological crystalline insulators imparts mass to Dirac electrons. The mass is shown to depend on the penetration depth of the surface states. Non-topological surface states are also reported.

Careful measurements of the zero-field quantum anomalous Hall effect find a less-precisely-quantized Hall conductivity than the integer quantum Hall effect. Here, the authors theoretically study the effects of nonlinear corrections to the Hall conductivity in both topological and trivial magnetic insulators.

The authors present electrical transport-based evidence of generalized Wigner crystal states in twisted bilayer MoSe₂ at fractional electron fillings ν = 2/5, 1/2, 3/5, 2/3, 8/9, 10/9, and 4/3, together with a Mott state at ν = 1. They further demonstrate continuous quantum melting transitions in a multi-parameter space of electron density, displacement and magnetic fields.

Anomalous conducting behavior of solids may reflect the presence of novel quantum states. Here, Zhang et al. report an increased conductivity in TaAs with a magnetic field applied along the direction of the current, which reveals an inherent property of the Weyl Fermion.

Monolayer graphene can support the quantum Hall effect up to room temperature. Here, the authors provide evidence that graphene encapsulated in hexagonal boron nitride realizes a novel transport regime where dissipation in the quantum Hall phase is mediated predominantly by electron-phonon scattering rather than disorder scattering.

The boundaries of fractional quantum Hall states can host multiple, interacting one-dimensional edge modes, which test our understanding of strongly interacting systems. Here the authors observe the edge-mode equilibration transition that was predicted for the ν=2/3 fractional quantum Hall state.

Here, twisted boron nitride is demonstrated to be a versatile moiré substrate for band structure engineering.

Using the valley degree of freedom in analogy to spin to encode qubits could be advantageous as many of the known decoherence mechanisms do not apply. Now long relaxation times are demonstrated for valley qubits in bilayer graphene quantum dots.

Small-angle twisted bilayer–bilayer graphene is tunable by the twist angle and electric and magnetic fields, and can be used to gain further insights into correlated states in two-dimensional superlattices.

Fractal Hofstadter bands have become widely accessible with the advent of moiré superlattices, exemplified by the square-lattice Hubbard-Hofstadter model. Here, the authors predict that, due to a combination of repulsive interactions and Van Hove singularities, this model can realize both nodal and chiral topological superconductivity for different band fillings.

This global meta-analysis of freshwater stressor–response relationships reveals that the biodiversity loss of five riverine organism groups reflects elevated salinity, oxygen depletion and fine sediment accumulation, while the relationship with nutrient enrichment and warming varies among groups.

In addition to the broken time-reversal symmetry that typifies Chern insulators, twisted bilayer graphene hosts a set of topological states with broken translational symmetry.

Creative experiences such as dance, music, drawing, and strategy video games might preserve brain health. The authors show that regular practice or short training in these activities is linked to brains that look younger and work more efficiently.

MOBSTER is an approach for subclonal reconstruction of tumors from cancer genomics data on the basis of models that combine machine learning with evolutionary theory, thus leading to more accurate evolutionary histories of tumors.

Light-induced phase transitions are typically described by a time-dependent mean-field theory. Here, the authors show that such a theory fails to capture the order parameter dynamics in a single layered manganite and discuss the role of disorder in ultrafast phase transitions in general.

Defects in liquid crystals play a central role in determining their structural and dynamic properties, whilst it is challenging to characterize the defects at a molecule level. Here, Gimet al. trace the evolution pathway of defects during a phase transition from a nematic to a smectic state.

A Dirac quantum spin liquid phase is predicted to have a continuum of fractionalized spinon excitations with a Dirac cone dispersion. A spin continuum consistent with this picture has now been observed in neutron scattering measurements.

Topological structures could spark promising functionalities in next generation nanoelectronics. Here, the authors report the realization of complex topological polar textures in epitaxial multiferroic BiFeO₃ –SrTiO₃ superlattices induced by competing electrical and mechanical boundary conditions.

A moiré quasicrystal constructed by twisting three layers of graphene with two different twist angles shows high tunability between a periodic-like regime at low energies and a strongly quasiperiodic regime at higher energies alongside strong interactions and superconductivity.

Naturally occurring 2H-stacked bilayer WSe₂ enables the observation of exciton condensates in the strong coupling limit.

Our understanding of the phase diagram of twisted graphene structures is incomplete. Now, twisted trilayer graphene is examined using a technique that locally images quantum oscillations and shows that a nematic semimetal is favoured at low density.

At equilibrium, the ferroelectric polarization is proportional to the strain. At ultrafast timescales, an above-bandgap laser excitation decouples strain and polarization, which, out of equilibrium, is mainly determined by the photoexcited electrons.

Metal-to-insulator transitions are characterized in twisted WSe, revealing strange metal behaviour and quantum criticality at low temperatures.

Tunable correlated states are observed in twist bilayer WSe₂ over a range of twist angles, with signatures of superconductivity for a twist of 5.1°.

Observing and tuning the Kondo effect in graphene is experimentally challenging. Here, the authors identify the spectroscopic signature of Kondo screening in graphene, along with a quantum phase transition between screened and unscreened phases of vacancy magnetic moments.

Whether the normal state electronic correlations in cuprates are responsible for superconductivity remains elusive. Here, Li et al. report that such correlations turn into a renormalized coherent state starting well above the superconducting transition, and it leads to a strengthened superconductive pairing.

Electron spins in quantum dots are a promising platform for quantum information technologies. Using a double quantum dot system with three electrons, Shi et al. show that certain pulse sequences allow for fast rotations to all possible states, improving the performance compared with the two electron case.

Artificial photonic graphene, a honeycomb array of evanescently coupled waveguides, has proven to be a useful tool for investigating graphene physics in various optical settings. Here, Song et al.demonstrate pseudospin-mediated vortex generation and topological charge flipping in otherwise uniform optical beams.

Phonons—quantized lattice vibrations in solids—carry energy and momentum through solids just like electrons, yet their control for technological means remains elusive. Towards this end, Kerfoot et al.show phonon-induced optical transparency in a quantum dot pair via electrically gated phonon dissipation.

Analogous to photonic crystals, phononic crystals can be used to engineer the acoustic properties of a system, however, creating nonlinear phononic crystals or nonlinear acoustic metamaterial is challenging. Here, Midtvedt et al.propose periodically pinned, atomically thin membranes as a nonlinear phononics platform.

Quantum tunnelling of the magnetisation limits the performance of single-molecule magnets at low temperatures. Here, the authors combine ab initio and analytical methods to show that spin-phonon coupling subtly influences tunnelling via polaron formation.