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Depolymerising polyolefins typically requires high temperatures and is energy intensive. Here, the authors upcycle PVC into a photothermal agent which could depolymerise polyolefins using sunlight into low molecular weight waxes or monomers

Developing new transformations of bulky chemicals is an important approach to expand the horizons of current chemistry. Instead of traditional hydroarylation of dienes, the authors herein demonstrate a nickel-catalyzed arylative telomerization of isoprene with high chemo- and regioselectivities.

Weyl semimetals are interesting because they are characterized by topological invariants, but specific examples discovered to date tend to have complicated band structures with many Weyl points. Here, the authors show that TaIrTe₄ has only four Weyl points, the minimal number required by time-reversal symmetry.

Proposals for the realization of Weyl semimetals, topologically non-trivial materials which host Weyl fermion quasiparticles, have faced demanding experimental requirements. Here, the authors predict such a state in stoichiometric TaAs, arising due to the breaking of inversion symmetry.

A superconducting material containing a topologically non-trivial electronic band structure presents the possibility of realizing Majorana states as well as exotic excitations with potential in quantum computing. Here, the authors evidence the required ingredients in the noncentrosymmetric superconductor BiPd.

Topological Dirac semimetals constitute a promising platform for the study of quantum Hall phenomena and Weyl fermion transport. Using high-resolution angle-resolved photoemission spectroscopy, Neupane et al. identify the topological bulk Dirac semimetal phase in a Cd₃As₂system.

Recently, the quantum anomalous Hall effect has been successfully achieved in the intrinsic magnetic topological insulator MnBi₂Te₄, but zero-field quantization has proved difficult to achieve due to poor sample quality. Here, the authors report zero-field quantization and chiral edge states in five-septuple-layer MnBi₂Te₄.

Optical chiral induction and spontaneous gyrotropic electronic order are realized in the transition-metal chalcogenide 1T-TiSe₂ by using illumination with mid-infrared circularly polarized light and simultaneous cooling below the critical temperature.

In the recently proposed topological crystalline insulators, the topological states result from crystalline symmetries rather than time-reversal symmetry. Xu et al. report the experimental observation of a topological crystalline insulator phase in Pb_1-xSn_xTe by spin-resolved photoemission spectroscopy.

In topological insulators, topology imposes a quantum phase transition between the trivial and nontrivial phases. Here, Xu et al. demonstrate how properties of the topological surface states emerge in the trivial phase of BiTl(S_1-δSe_δ)₂when close to its chemically tuned phase transition.

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.

The dynamical axion quasiparticle, which is directly analogous to the hypothetical fundamental axion particle, is observed in two-dimensional MnBi₂Te₄, and has implications for quantum chromodynamics, cosmology and string theory.

The authors demonstrate control of antiferromagnetic order using helical light.

Experiments show that niobium arsenide is a Weyl semimetal.

Broadband terahertz emission from a two-dimensional van der Waals ferroelectric semiconductor, NbOI₂, offers opportunities towards nanoscale near-field terahertz spectroscopy and in situ probing of quantum collective excitations in two-dimensional materials.

A photocurrent enhancement at the charge neutrality point is observed in graphene when the Fermi level matches the Dirac point.

An antiferromagnetic diode effect was observed in a centrosymmetric crystal without directional charge separation. This effect could be used to create in-plane field-effect transistors and microwave-energy-harvesting devices.

A new type of Hall effect—the layer Hall effect—is produced in a 2D antiferromagnet that does not exhibit any net magnetization.

Topological insulators are bulk insulators beneath conducting surface states with very special properties. By doping these surface states with iron, the surface band structure can be explored and controlled.

When doped with copper, the topological insulator Bi₂Se₃ becomes superconducting. But for new physics and applications the search is not for just any superconductor; the material must retain its topological character. And indeed that is the case with doped Bi₂Se₃.

Causality, the relationship between cause and effect, is a central concept in Einstein’s theory of relativity. Here, authors show that a causality analogue in energy-momentum space plays an important role in describing quasiparticle interactions in quantum matter.

The search for magnetic Weyl fermion remains a challenge. Here, the authors report angle-resolved photoemission spectroscopy and magnetotransport measurements resolving the topological properties of Weyl fermion quasiparticles in magnetic non-centrosymmetric crystal PrAlGe.

A study reports a dual quantum spin Hall insulator in monolayer TaIrTe₄, arising from the interplay of its single-particle topology and density-tuned electron correlations.

Here the authors demonstrate a broadband nonlinear optical diode effect and its electric control in the magnetic Weyl semimetal CeAlSi. Their findings advance ongoing research to identify novel optical phenomena in topological materials.

We report the experimental realization and room-temperature operation of a low-power (20 pW) moiré synaptic transistor based on an asymmetric bilayer graphene/hexagonal boron nitride moiré heterostructure.

Kramers–Weyl fermions are identified in chiral crystals, and their phenomenology is drawn out.

Electronic ferroelectricity is observed in a graphene-based moiré heterostructure, which is explained using a spontaneous interlayer charge-transfer model driven by layer-specific on-site Coulomb repulsion.

Nodal-line shaped bands appearing near the Fermi level host unique properties in topological matter, which has yet to be confirmed in real materials. Here, the authors report the existence of topological nodal-line states in the non-centrosymmetric single-crystalline spin-orbit semimetal PbTaSe₂.

Single layers of atoms can exhibit electronic properties far removed from their three-dimensional counter parts, with much potential for spintronics. Here, the authors provide evidence of spin-orbit splitting and extrinsic quantum well states in MoS2 and MoSe2 by angle-resolved photoemission spectroscopy

Two-dimensional materials provide possible platforms to map exotic phenomena from particle physics to condensed matter physics. Here, the authors predict doping dependent electronic behaviour in Mo_xW_1−xTe₂, in resemblance of a phenomenon which is believed to exist only in particle physics.

A Type II Weyl fermion semimetal has been predicted in Mo_xW_1−xTe₂, but it awaits experimental evidence. Here, Belopolski et al. observe a topological Fermi arc in Mo_xW_1−xTe₂, showing it originates from a Type II Weyl fermion and offering a new platform to study novel transport phenomena in Weyl semimetals.

Electromagnetic response of topological materials is described the so called axion electrodynamics which contains additional relations between the fields. Here the authors extend the theory of axion electrodynamics to general optical frequencies and apply it to a realistic topological antiferromagnet.

Films of the correlated oxide NdNiO₃ form a metallic antiferromagnetic phase that can be identified using electrical currents, raising the prospect of applications in spintronics.

In solids, the quantum metric captures the quantum coherence of the electron wavefunctions. Recent experiments demonstrate the detection and manipulation of the quantum metric in a noncollinear topological antiferromagnet at room temperature.

The nonlinear Hall effect is observed in bilayer WTe₂ in the absence of a magnetic field, providing a direct measure of the dipole moment of the Berry curvature.

A new type of surface state has recently been reported in ZrSiSe but its physical properties remain unclear. Here, Zhu, Chang, Huang, et al. report rotational symmetry breaking, healing effect and anomalous Umklapp scattering arising from the nonsymmorphic effect of the floating band state on ZrSiSe (001) surface.

Breaking the time-reversal symmetry of the surface states of topological insulators is predicted to produce many exotic and potentially useful phenomena. Spin-resolved angle-resolved photoemission spectroscopy spectra reveal that magnetic dopants can induce such symmetry breaking in Be₂Se₃ thin films.

In three-dimensional metals, topological objects known as Weyl nodes can arise from a crossing of the conduction and valence bands. Experiments under high magnetic fields show how Weyl nodes of opposite chiralities can move together to annihilate.

Supersymmetry and Majorana fermions that are their own antiparticles are both concepts from particle physics that may become testable in condensed-matter systems. The observation of Cooper pairs in a helical Dirac gas brings this goal a step closer.

Strong bulk van der Waals materials are fabricated by the compressive moulding of two-dimensional nanosheets near room temperature through water-mediated densification, providing an energy-efficient way for synthesizing various van der Waals materials and a potential for tailoring compositions.

Optoelectronic experiments show that a monolayer of WTe₂ is a material that simultaneously has topological electronic states and electron wavefunctions with a dipole in their Berry curvature.

Measuring the photocurrent response to circularly polarized mid-infrared light provides direct access to the chirality of Weyl fermions in Weyl semimetals — the property responsible for a range of exotic phenomena.

The non-collinear spin structure and nontrivial Berry curvature of Mn₃Ge give rise to a long-range supercurrent in superconductor–Mn₃Ge–superconductor lateral Josephson junctions.

High extraction capacity with precise selectivity to trace amounts of gold over a wide range of co-existing elements remains a challenge for effective e-waste recycling. Here, authors demonstrate the excellent performance of rGO for gold extraction from e-waste leachate, even at minute concentrations.

Angle-resolved photoemission spectroscopy measurements reveal that CoSi and RhSi are nearly ideal topological conductors, with structural chirality and surface helicoid arcs of topological charge ±2 arising from bulk multifold chiral states.