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In most metals the optical Hall effect is very small at visible wavelengths, and usually can only be observed at low frequencies. Here, Am-Shalom et al present a technique involving a large amplitude modulation of the external magnetic field, allowing for the measurement of the optical Hall effect in a range of metals at visible wavelengths.

In episode 1 of What’s in a name we look at how species are named, and whether the current system needs to evolve in the face of societal pressure.

Electron pairing is of fundamental interest in condensed matter physics. Here, the authors demonstrate electrons forming not only pairs - but also triplets - in graphene quantum Hall Fabry-Pérot interferometers.

Ohmic contacts to n-type molybdenum disulfide can be created over a temperature range from millikelvins to 300 K using a window-contacted technique, which leads to evidence for fractional quantum Hall states at filling fractions of 4/5 and 2/5 in the lowest Landau levels of bilayer molybdenum disulfide devices.

Ultra-narrow quantum Hall Josephson junctions defined in encapsulated graphene nanoribbons exhibit a chiral supercurrent, visible up to 8  T.

Similar to optical waves, electrons can also interfere, but they require high-quality devices with minimal scattering for an experimental observation of this effect. An interferometer based on a single sheet of graphene provides an alternative to the more standard semiconductor devices and may in future enable access to exotic quantum effects, such as anyon braiding.

Quantum point contacts are gate-tunable constrictions allowing for control of charge carrier transmission in 2D electron gases. Here, the authors fabricate a hBN/graphene/hBN van der Waals heterojunction to enable quantum point contact devices in the integer and fractional quantum Hall regimes.

Three tunable quantum Hall broken-symmetry states in charge-neutral graphene are identified by visualizing their lattice-scale order with scanning tunnelling microscopy and spectroscopy.

Planning for the Colorado River is critical to secure water and hydropower for the western US under climate change. This study highlights how different policies may reduce but not eliminate the risk of losing water and energy supply altogether.

Electrons hopping in two-dimensional honeycomb lattices possess a valley degree of freedom. Here, the authors observe room-temperature valley Hall transport without any extrinsic symmetry breaking in the non-centrosymmetric monolayer and trilayer MoS₂ by purely electronic means, whereas no valley signal is detected for centrosymmetric bilayer MoS₂.

One way of producing Majorana fermions for topological quantum computing is to induce superconductivity in other topological states. Here, the proximity effect does this for the quantum spin Hall effect state in a 2D material.

Experiments show that when driven by electric currents, magnetic skyrmions experience transverse motion due to their topological charge — similar to the conventional Hall effect experienced by charged particles in a perpendicular magnetic field.

Applying magnetic and electric fields to twisted bilayer graphene creates an electron–hole bilayer that features helical 1D edge modes and fractional quantum Hall states.

A phase of strongly interacting electrons that has a spontaneous dipole moment is seen for the first time using an approach that images the electron's wavefunction through interference at an impurity.

Experiments show that when driven by electric currents, magnetic skyrmions experience transverse motion due to their topological charge — similar to the conventional Hall effect experienced by charged particles in a perpendicular magnetic field.

In this four-part podcast series, Nature follows two scientists to find what it takes to launch a research lab.

A free-living trial in people with overweight or obesity found that minimally processed diets led to greater weight loss and cardiometabolic improvements than ultraprocessed diets following UK healthy eating guidelines at 8 weeks.

Researchers use a chimeric approach to reveal the first near-atomic resolution structures the yellow fever virion, showing key differences between vaccine and virulent strains that affect how antibodies recognise and neutralise the virus.

3D higher-order topological insulators (HOTIs) exhibit 1D hinge states depending on extrinsic sample details, while intrinsic features of HOTIs remain unknown. Here, K.S. Lin et al. introduce the framework of spin-resolved topology to show that helical HOTIs can realize a doubled axion insulator phase with nontrivial partial axion angles.

Fe₃Sn₂ hosts very robust magnetic skyrmions, stabilized via frustration, rather than the typical Dzyaloshinskii-Moriya interaction. Here, Bernstein et al. using a spin torque skyrmion resonance, detect key features of this skyrmion phase in the observed resonances, and find that this can be tuned via an applied current.

Scanning tunnelling microscopy shows that 1D channels between quantum Hall states with different valley polarization are metallic or insulating depending on constraints imposed on electron–electron interaction by valley flavour.

The quantum Hall effect is thought to exist only in two-dimensional materials. Here, transport measurements show that thin graphite slabs have a 2.5-dimensional version, with a parity effect for samples with odd and even number of layers.

The authors report resonant soft x-ray scattering and polarimetry measurements on epitaxial thin films of La3Ni2O7. They find a diagonal bicollinear double spin stripe order, with no evidence of charge modulation.

The hierarchy of symmetry breaking in magic-angle twisted bilayer graphene remains a topic of intense fundamental study. Here, the authors determine the spin polarization of symmetry-broken quantum Hall states and Chern insulators in MATBG using a twist-decoupled graphene probe.

Analysis of soundscape data from 139 globally distributed sites reveals that sounds of biological origin exhibit predictable rhythms depending on location and season, whereas sounds of anthropogenic origin are less predictable. Comparisons between paired urban–rural sites show that urban green spaces are noisier and dominated by sounds of technological origin.

Many topological crystalline phases have unknown physical responses. Here, the authors systematically extend the theory of defect and flux responses to predict zero-dimensional (0D) states in topological crystalline materials, including 2D PbTe monolayers and 3D SnTe.

Magnetic scattering may profoundly modify the electronic properties of a topological insulator. Here, Nam et al. report a method enabling separation of the effects of magnetic and non-magnetic scattering by decorating the surface of topological insulators with molecules.

Heavy pnictogen-based compounds are promising nontoxic and stable alternatives to lead-halide perovskites, but are limited by carrier localization. Here, by investigating CuSbSe₂, the authors identify how this limitation could be avoided.

The valley Hall effect in transition metal dichalcogenides has been studied as a potential mean to develop new electronic and optoelectronic devices. The authors theoretically demonstrate that valley Hall effect can be derived from spin degrees of freedom, which is distinct from the conventional orbital related type.

Understanding deregulation of biological pathways in cancer can provide insight into disease etiology and potential therapies. Here, as part of the PanCancer Analysis of Whole Genomes (PCAWG) consortium, the authors present pathway and network analysis of 2583 whole cancer genomes from 27 tumour types.

Moire bilayers support quantum spin Hall (QSH) and quantum anomalous Hall (QAH) states, but a unified explanation is missing. Mai et al. show that by including interactions in typical models, the QSH state shifts from 1/2 to 1/4 filling and gives way to the QAH state at low temperature.

High-quality rhombohedral graphite films are found to offer an alternative to twisted bilayer graphene as a platform for studying correlated physics in carbon materials.

A global network of researchers was formed to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity; this paper reports 13 genome-wide significant loci and potentially actionable mechanisms in response to infection.

Magnetic skyrmions are topological spin textures that hold potential for the development of post-von Neumann computing schemes. In coupled ferrimagnetic insulators, pinning effects and intentional distortions can lead to a ratchet-like current-driven motion of skyrmion bubbles.

Genome-wide analyses identify 30 independent loci associated with obsessive–compulsive disorder, highlighting genetic overlap with other psychiatric disorders and implicating putative effector genes and cell types contributing to its etiology.

Repurposing a microbial system to deliver molecules directly into cells, and the disconnect between research into, and treatment of, chronic pain.

The presence of disorder makes it difficult to determine the intrinsic properties of graphene in its ideal form. Measurements of high-quality bilayer graphene flakes suspended above a substrate identify the persistence of quantum Hall behaviour at magnetic fields an order of magnitude lower than seen before, and previously unseen symmetry breaking of the lowest Landau level is also observed.

Disorder leads to localization of electrons at low temperatures, changing metals to insulators. In a superconductor the electrons are paired up, and scanning tunnelling microscopy shows that the pairs localize together rather than breaking up and forming localized single electrons in the insulating state.

An analysis of 24,202 critical cases of COVID-19 identifies potentially druggable targets in inflammatory signalling (JAK1), monocyte–macrophage activation and endothelial permeability (PDE4A), immunometabolism (SLC2A5 and AK5), and host factors required for viral entry and replication (TMPRSS2 and RAB2A).

In high-temperature superconductors, a very low density of states, the pseudogap, exists even above the critical temperature. Here, the authors show that this is also the case for a conventional superconductor, titanium nitride thin films, and that this pseudogap is induced by superconducting fluctuations.

A distinct population of CD4 T cells resides in specific regions of the steady-state brain, and these T cells are programmed in the periphery by the microbiome to coordinate adaptive behaviour.