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Fermionic currents of opposing chirality can be spatially filtered without the need for a magnetic field using the quantum geometry of topological bands in single-crystal PdGa.

Interwoven magnetic and non-magnetic layers in TbTi₃Bi₄ overcome kagome frustration, producing coupled elliptical-spiral magnetic and spin-density-wave orders and a very large anomalous Hall effect driven by strong electron–magnetic field interactions.

Over the past 40 years, the quantum Hall effect (QHE) has inspired new theories and led to experimental discoveries in a range of fields going beyond solid-state electronics to photonics and quantum entanglement. In this Viewpoint, physicists reflect on how the QHE has influenced their research.

Using a tuning fork-based probe, the authors offer evidence of 2D magnetic moment along the c-axis of CsV₃Sb₅. Their findings suggest that loop currents within the kagome lattice can generate orbital magnetism.

The magnetoresistance suggests an exotic topological phase in LaBi, but the evidence is still missing. Here, Nayaket al. report the existence of surface states of LaBi through the observation of three Dirac cones, confirming it a topological semimetal.

Crystal structures with two sublattice pairs per primitive cell can host so-called dark states which interact minimally with light due to destructive interference. Here, the authors reveal that in the semiconductor (NbSe₄)₃I these states lead to an indirect-gap optical behavior, despite the band structure displaying an almost direct band gap, having significant impact on its optoelectronic properties.

Many kagome metals exhibit a sublinear temperature dependence in resistivity up to room temperature. Here, the authors propose a semiclassical two-pocket theory consisting of a Dirac cone and Van Hove singularity to explain this behavior.

Materials which simultaneously exhibit superconductivity and topologically non-trivial electronic band structure possess potential applications in quantum computing but have yet to be found. Here, the authors find superconductivity in MoTe₂, a material predicted to be topologically non-trivial.

A new class of moiré materials based on monolayers with triangular lattices and low-energy states at the M points of the Brillouin zone is introduced, demonstrating emergent momentum-space non-symmorphic symmetries, a kagome plane-wave lattice structure, and potential quasi-one-dimensionality.

Ferromagnetic systems rarely display a large or non-saturating magnetoresistance, due to the low Fermi velocity of the predominant charge carrier. Here, the authors show that MnBi, a ferromagnet, bucks this trend, showing both large and non-saturating magnetoresistance, and high charge carrier motilities.

Magnetic Weyl semimetals in the 2D limit may behave like 2D Chern insulators and host the quantum anomalous Hall effect at high temperatures. Here, the authors report the observation of linearly dispersing topological states confined to the edges of the kagome Co₃Sn terraces in the magnetic Weyl system Co₃Sn₂S₂.

Interpretation of the physical phenomena observed in non-collinear antiferromagnets is challenging; imaging and writing magnetic domains is important for applications. Here the authors show magnetic domain imaging and writing in a non-collinear antiferromagnet by recording anomalous Nernst voltage in response to a localized thermal gradient.

Magnetic anti-skyrmions—chiral spin textures that could find applications in spintronics—have been recently observed in inverse tetragonal Heusler Mn_1.4Pt_0.9Pd_0.1Sn. Here, the authors observe anti-skyrmions in thin films of Mn_1.4Pt_0.9Pd_0.1Sn over a wide range of temperature and magnetic fields.

Topological quasiparticle with higher Chern number is promising to realize large-quantized photogalvanic effect. Here, the authors observe splitting of both topological surface and bulk states in a chiral crystal PtGa, suggesting multifold fermions with a maximal Chern number of ±4.

Direct visualization of chiral effects in topological chiral semimetals remains elusive. Here, Sessi et al. demonstrate that quasiparticle scattering at impurities in the two enantiomers of PdGa gives rise to handedness dependent quantum interference patterns.

In some materials electrons can behave hydrodynamically, exhibiting phenomena associated with classical viscous fluids. In this theory work, the authors show that the symmetries of the crystal lattices in which the electrons reside can lead to additional unique hydrodynamic effects.

Experimental evidence of coherent charge transport in the normal state of the kagome metal CsV₃Sb₅ is presented, revealing the nature of correlated order in kagome metals and new directions for exploring quantum coherence in correlated electron systems.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) are emerging candidates for organic 2D crystal materials, but the precise implantation of chirality has yet to be demonstrated. Here, the authors report a side chain-induced chirality amplification strategy to achieve tunable chiral expression in 2D c-MOFs.

Aliovalent doping affects the electrical properties of semiconductors, but its effect on phonons is unclear. Now, strong softening and deceleration of phonons, causing a significant reduction in lattice thermal conductivity, is reported for Hf-doped NbFeSb.

Recent work has expanded the concept of altermagnets to non-collinear magnetic materials. Here, Hu et al extend this further to non-collinear chiral materials, determining altermagnetic multipolar order parameters and predicting that such materials host large spin-hall and Edelstein effects.

The electron-hole compensation hinders the magneto-Seebeck coefficient of topological semimetals. Here, authors report simultaneous high longitudinal and transverse thermopowers in a TaAs₂ single crystal by a multipocket synergy strategy.

Applying a magnetic field to the topological material Bi₈₈Sb₁₂ enhances the Seebeck coefficient, resulting in a high thermoelectric figure of merit zT of 1.7 at 180 K and 0.7 T.

Oxygen evolution is a key reaction in electrolysers and involves a spin-dependent, multi-electron transfer process. Here the authors use topological semimetals with intrinsic chirality as a means to control spin in oxygen evolution catalysts, and explore the role of spin–orbit coupling in determining activity.

Chiral topological materials have been predicted to host orbital angular momentum monopoles, which can be useful for orbitronics applications. Now such monopoles have been imaged in chiral materials.

The authors study kagome superconductor LaRu3Si2 under pressure up to 40 GPa. They find a superconducting dome as a function of pressure, with Tc reaching its maximum when the coexisting charge order remains long-range.

Theory predicts that phonons—quanta of lattice vibrations—can carry finite angular momentum and thus influence physical properties of materials. Now phonons with angular momentum have been seen in tellurium with a chiral crystal structure.

The mechanism of the multiple-q charge density wave phase in the antiferromagnetic kagome metal FeGe is not fully understood. Here the authors reveal dimerization-driven hexagonal charge-diffuse precursor and identify the fraction of dimerized/undimerized states as the key order parameter of the phase transition.

Topological insulators have been predicted and recently demonstrated experimentally in a series of binary alloys. It is now show theoretically that about 50 Heusler compounds show features similar to those of the confirmed topological insulator HgTe, which considerably expands the possibility of realizing quantum topological phenomena.

Flexible thermoelectrics are of great interest with increasing demand of flexible and wearable electronics. Here, the authors demonstrate that the Weyl semimetal, WTe2, has a high Nernst power factor and great mechanical flexibility.

The development of robust catalysts that could work under industrial-scale current densities is a challenge for hydrogen production. Here, the authors report an in-situ activation method to produce ferromagnetic Ru clusters that can catalyze the hydrogen evolution reaction at high current densities.

The half-Heusler GdPtBi is found to show transport and calorimetric signatures of the existence of Weyl fermions under the application of a magnetic field. The half-Heusler alloys form a big family of tunable compounds that may substantially enlarge the number of Weyl semimetals known.

The anomalous Nernst effect (ANE) in topological materials with large Berry curvature shows great potential for transverse thermoelectrics, but antiferromagnets typically show small ANEs. The antiferromagnet YbMnBi₂ has an ANE thermopower of 3 μV K⁻¹, similar to ferromagnets, and a larger ANE conductivity.

Periodic laser light can modify the electronic properties of solids and offers a path to create new material phases. In a topological antiferromagnet, periodic driving with opposite light helicities is now shown to produce distinct Dirac mass gaps.

Electrical transport measurements reveal that Co₃Sn₂S₂ is probably a magnetic Weyl semimetal, and hosts the highest simultaneous anomalous Hall conductivity and anomalous Hall angle. This is driven by the strong Berry curvature near the Weyl points.

Distinguishing band and Mott insulators experimentally represents a longstanding challenge. Here, the authors demonstrate a momentum-resolved signature of a dimerized Mott-insulator in the out-of-plane spectral function of Nb₃Br₈.

Valley anisotropy is proposed theoretically to benefit the electrical transport of thermoelectric materials but it lacks experimental demonstration. Here, the authors demonstrate how to utilize the single anisotropic Fermi pocket in p-type Mg₃Sb₂ to enhance its thermoelectric properties.

Semimetals with the band structure exhibiting Dirac and Weyl crossings can show special electronic and magnetic properties. Here the authors explore the electronic properties of the type-II Weyl semimetals, MoP₂ and WP₂ with robust Weyl points which display very high magnetoresistance and conductivity.

The anomalous Hall angle parameter tanθ^A can be formulated as a function of the product of electrical resistivity and anomalous Hall conductivity, a scheme that allows the anomalous Hall angle in the magnetic Weyl semimetal Co₃Sn₂S₂ to be increased to 25°.

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.

Weyl fermions are chiral massless fermions with interesting exotic properties. Here, chlorine doping of Co₃Sn₂S₂ single crystals is found to shift the Fermi energy towards the Weyl points, enhancing its Weyl semimetal signatures such as a ninefold increase in magnetoresistance and a significantly larger anomalous Hall conductivity.

Kagome-lattice systems host a variety of condensed matter phenomena. Here, the authors use NMR spectroscopy to probe the orbital-selective modulations of the local density of states in the charge density wave phase of ScV₆Sn₆.

An approach to design compensated ferrimagnetic Heusler alloys is established. A small lack of compensation produces giant exchange bias and large coercivity. This effect is observed for alloys that have the magnetic transition above room temperature.

Weyl semimetals are predicted to exhibit a host of unusual transport properties. NbP, a system predicted to share characteristics of both normal and Weyl semimetals, is now shown to have a very large, non-saturating magnetoresistance.