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Evidence for spin chirality fluctuations in two-dimensional ferromagnets is provided by magnetotransport measurements.

Topological insulators are exotic states of matter that show quantum-Hall-like behaviour in the absence of a magnetic field. Surface states in such systems are protected against scattering and are thought to provide an avenue for the realization of fault-tolerant quantum computing. Experiments now reveal the observation of such a topological state of matter in Bi₂Se₃, a naturally occurring stoichiometric material with a simple surface-state structure and a bulk energy gap larger than k_BT at room temperature.

The key to exploiting quantum materials for applications is the control of their properties. This Review discusses strategies to externally modify their properties on demand.

The authors study a liquid crystal microcavity with polarization-dependent absorption, a source of non-Hermiticity. The transition in the Hermitian topology of the spin-orbit coupling makes possible the annihilation of exceptional points.

Axial fields couple to the states of different chiralities with opposite signs. In an acoustic Weyl system, the implementation of such fields induces chiral Landau levels, which is now observed experimentally.

Declining Arctic sea ice is increasing polar bear land use. Here, the authors follow 20 different polar bears on land over 3 years and measure daily energy expenditure finding that despite behavioural and diet plasticity the bears are at risk of starvation.

A method to control the topological properties of two-dimensional (2D) materials on few-femtosecond timescales is proposed. By controlling the sub-cycle structure of non-resonant driving fields, it may be possible to coherently write, manipulate and read selective valley excitation.

What makes the phonons in cuprates become chiral, as measured by their thermal Hall effect, is an unresolved question. Here, the authors rule out two extrinsic mechanisms and argue that chirality comes from a coupling of acoustic phonons to the intrinsic excitations of the CuO₂ planes.

Advanced materials are characterized by complex mathematical properties such as the topology and geometry of quantum states. This work demonstrates that in some systems, the evolution of a particle’s spatial distribution is a direct measure of these properties: the relative displacement in two sublattices is found to be given by the quantum metric.

A tunable quantum dot device in Bernal bilayer graphene possesses a spin–valley relaxation time of 38 s at millikelvin temperatures.

An analysis of T cell responses in people with amyotrophic lateral sclerosis shows that the C9orf72 antigen is a key target of autoimmune responses in the disease, and identifies C9orf72 epitopes that are recognized.

A second-order topological Weyl semimetal based on a 3D-printed acoustic crystal, exhibiting Weyl points, Fermi arc surface states, and hinge states, has been experimentally demonstrated.

Applying the mathematical concept of topology to the wave-vector space of photonics yields exciting opportunities for creating new states of light with useful properties such as unidirectional propagation and the ability to flow around imperfections.

A topological insulator illuminated with circularly or linearly polarized light produces a photocurrent that depends on the helicity or polarization of the light, respectively.

The control of different types of magnetic order is central to the study and development of spintronic devices. Here, the authors evidence an exchange-stabilized helix state with a low energy barrier for reversal in a room-temperature antiferromagnetic Heusler material.

Understanding the spin texture of topological insulator surface states is crucial for applications in spintronics and nanodevices. Here, Neupane et al. report systematic spin- and angle-resolved photoemission spectroscopy on ultrathin Bi₂Se₃films for the first time.

Single layers of carbon atoms are now well known for their useful properties, but a combination of two sheets can also exhibit some unusual electronic characteristics. Here, the authors identify two distinct electron states in bilayer graphene that result from spontaneous symmetry breaking.

Atomic Bose–Einstein condensates can be used to study many-body phenomena that occur in more complex material systems; however, the charge neutrality of these systems prevents intriguing phenomena that occur for charged particles in a magnetic field. Rotation can be used to create a synthetic magnetic field, but such fields are of limited strength. An optically synthesized magnetic field for ultracold neutral atoms that is not subject to the limitations of rotating systems is now experimentally realized.

There is an ongoing debate in the origin of unusual bumps in the resistive Hall measurements in SrRuO3 systems. Here, the authors analyze surface inversion symmetry breaking and confirm the role of an interfacial Dzyaloshinskii–Moriya interaction at the heart of the system, revealing a magnetic spin crystal emergent across the unusual bumps.

Non-equilibrium signatures of topology—the appearance, movement and annihilation of vortices in a cold-atom system—are identified, showing that topological phase can emerge dynamically from a non-topological state.

Solar photovoltaics is entering a multi-terawatt era, driven by decades of cost, performance and reliability gains. In this Perspective Alberi et al. discuss the role of historical and future learning, highlighting the increasing importance of sustainability considerations.

Mucosal influenza vaccines promise enhanced protection but lack defined immune correlates of protection. Here, the authors conduct a phase I trial of an intranasal recombinant influenza A/H5 vaccine with a nanoemulsion adjuvant, demonstrating successful mucosal priming and broad cross-clade immune responses, advancing the development of intranasal influenza vaccines.

Weyl semimetals exhibit exotic properties owing to the presence of Weyl fermions. Here, Xu et al. show that tantalum phosphide is an ideal platform for studying the transport properties of these particles because its low-energy properties are dominated by a single type of Weyl fermion.

A structure of monolayer and bilayer graphene with a small twist between them shows correlated insulating states that can be tuned by changing the twist angle or applying an electric field.

Many-body interactions typically involve spontaneous symmetry breaking and the breakdown of simple single-particle models. Lee et al. now show that trilayer-graphene devices are a tunable platform for investigating the transition between these two regimes.

Here the authors define an inter-protomeric mechanism of deglycosylation of human IgG antibodies for corynebacterial IgG-specific ENGases and demonstrate that in vivo CU43 treatment preserve the neutralizing capacity of anti-influenza IgG antibodies.

The polarization state of light is analogous to the spin state of electrons, enabling equivalent phenomena to be explored in optics as in the solid state. Here, the authors study directional scattering of light from nanostructured surfaces, arising from a spin-orbit coupling effect for surface plasmon waves.

The benefits and risks of nature to human health have been studied, however, robust empirical research on forest biodiversity and health outcomes is still lacking. Here the authors use a unique dataset from 164 European forest stands to explore the associations between forest types and well-being.

A magnetic field and temperature gradient produce a large electric potential in a ferromagnet, indicating the possible presence of Weyl points. The specific structure of Weyl points gives the electrons quantum-critical properties.

The quark structure of the f₀(980) hadron is still unknown after 50 years of its discovery. Here, the CMS Collaboration reports a measurement of the elliptic flow of the f₀(980) state in proton-lead collisions at a nucleon-nucleon centre-of-mass energy of 8.16 TeV, providing strong evidence that the state is an ordinary meson.

Sub-cycle phase-resolved attosecond interferometry is developed. The obtained phase information enables us to decouple the multiple quantum paths induced in a light-driven system, isolating their coherent contribution and retrieving their temporal evolution.

Most of the notable properties of graphene are a result of the cone-like nature of the points in its electronic structure where its conduction and valance bands meet. Similar structures arise in 2D HgTe quantum wells, but without the spin- and valley-degeneracy of graphene; their properties are also likely to be easier to control.

Skyrmions are topologically protected field configurations that appear as solutions of continuous quantum-field theories. Recently, they have been observed in magnetic bulk alloys, where a lattice of skyrmions is stabilized by an external magnetic field. In contrast, this study finds evidence for a skyrmion lattice as a spontaneous ground state, encoded into a magnetic spin texture on the atomic scale.