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The dynamics of hole-conjugated fractional quantum Hall states is poorly understood due to the limitations of current experimental probes. Here the authors study the high-frequency dynamics of edge modes at filling factor 2/3, precisely identifying the tunneling charge and damping of constituent charge modes.

Spin-orbit torques are a well-established method for the control of magnetization, the key ingredients for conventional spin-orbit torques being a conductive material with a strong spin-orbit interaction. Here, Tang, Zhang and Cheng show that in antiferromagnetic insulators, the topological phase can support a unique form of Neel spin-orbit torque driven by adiabatic currents, which suppresses joule heating.

Graphene was one of the first materials proposed to host the quantum spin Hall effect. However, its weak intrinsic spin-orbit interaction means that observing such an effect requires modifying the graphene band structure. Here, Ghiasi et al. combine graphene with CrPS₄ and detect quantum spin Hall states at zero magnetic field.

Superlattices, with a length scale and structure that differs from the parent lattice of the host material, are well-known to allow for remarkable new electronic and magnetic properties. Here, Xie et al. synthesize Cr_1/4TaS₂, and find that it exhibits an unusual anomalous Hall effect below the Néel temperature even in stoichiometric high-quality crystals.

Tilgner et al. demonstrated the formation of the quantum spin Hall insulator bismuthene on SiC, intercalated underneath a protective graphene layer. A hydrogen-induced orbital filtering effect is the driving force behind this reversible phase transition.

Electronic correlation, geometric frustration, and topology are known to individually drive intriguing properties in materials. Here, the authors explore these interactions in the quasi-kagome Kondo Weyl semimetal Ce₃TiSb₅, revealing unconventional Hall effects that underscore the complex interplay of these factors, with implications for understanding topological and magnetic phenomena

Previous models explain solid-solution strengthening by differences in atomic volume and electronegativity of the constituent atoms. Here, the authors consider both factors simultaneously and identify atomic volume as the dominant factor for FCC alloys.

Intrinsic anomalous Hall effect has been observed in twisted graphene multilayers, but these structures are typically not energetically favorable. This study extends these observations to Bernal-stacked tetralayer graphene, which is the most stable configuration of four-layer graphene.

Using a system to adjust the strength of cavity vacuum fields penetrating a Hall bar, a study describes the effect of the vacuum field of a cavity on electronic correlations in quantum Hall systems.

Magnetically intercalated transition metal dichalcogenides provide a platform to study the interplay of magnetism, electronic band structures, and correlations. Here the authors demonstrate a nearly magnetization-free anomalous Hall effect, collinear antiferromagnetism and non-Fermi liquid behavior in V_1/3NbS₂.

The complex electronic motion in the quantum Hall regime in semiconductors has so far eluded analysis of its microscopic structure. Here, the authors use scanning gate microscopy to measure the spatial structure of transport inside a metal in this regime, opening the way for localized manipulation of the electronic states.

The current known two-dimensional topological insulators with small band gaps limit the potential for room temperature applications. Here, Chen et al. observe a sizable gap of 129 meV in a 1T'-WSe₂ single layer grown on bilayer graphene with in-gap edge state near the layer boundary.

The anomalous Hall effect is a macroscopic manifestation of a quantum mechanical effect. Here, Uelandet al. report the observation of a high Hall conductivity in the heavy-fermion compound UCu5, a metallic system, and explain its origin in terms of geometric frustration effects.

Graphene on boron nitride gives rise to a moiré superlattice displaying the Hofstadter butterfly: a fractal dependence of energy bands on external magnetic fields. Now, by means of capacitance spectroscopy, further aspects of this system are revealed—most notably, suppression of quantum Hall antiferromagnetism at particular commensurate magnetic fluxes.

The spin Hall effect and its inverse allow conversion between charge and spin currents in both magnetic and nonmagnetic materials. Weiet al.observe an anomaly in the temperature dependence of the inverse spin Hall effect, which suggests that it can also be used as a sensor for very small magnetic moments.

It is predicted that fractionally charged skyrmions, topologically protected vortex-like spin configurations, may exist in systems exhibiting fractional quantum Hall states. Here, the authors demonstrate the existence of such objects in GaAs single quantum wells.

Previous work has shown that helical domain walls can form between states of different spin-polarization during a ferromagnetic spin transition in the fractional quantum Hall regime. Here, the authors study the transport through a single helical domain wall and find strong deviations from a simplified theory of weakly interacting edge channels.

Dirac fermions at ap–njunction can exhibit a wide variety of unusual properties. Here, the authors investigate the dynamics of such fermions in a graphene junction using shot noise measurements and demonstrate the crucial role of junction length.

A magnetoresistance effect that occurs in a platinum layer deposited on a magnon junction consisting of two insulating magnetic yttrium iron garnet layers separated by an antiferromagnetic nickel oxide spacer layer could be used to create spintronic and magnonic devices that are free from Joule heating.

A technique that allows the electrical detection of spin-polarized transport in semiconductors without disturbing the spin-polarized current or using magnetic elements has now been demonstrated. The approach could lead to the integration of spintronics elements into semiconductor microelectronic circuits.

Monolayer graphene in the quantum Hall regime exhibits a third-order nonlinear Hall response, which is robust against variations in magnetic field and temperature and provides insights into the interaction of chiral edge states.

The quantum Hall effect takes place in a two-dimensional electron gas under a strong magnetic field and involves current flow along the edges of the sample. In the fractional regime, counter-propagating modes that carry energy but not charge — the so-called neutral modes — have been predicted but never observed. These authors report the first direct observation of these elusive modes.

Metamaterials enable the control and manipulation of light on subwavelength scales, allowing numerous optical device applications. Here, the authors show the selective excitation of spatially confined modes in an anisotropic hyperbolic metamaterial, based on the photonic spin Hall effect.

Fractional quantum Hall states in 2D electron gases arise due to strong electron-electron interactions, which makes a general theoretical understanding difficult. Fu et al. present data showing the ν = 5/3 quantum Hall state has a 3/2 plateau in the diagonal resistance that has not been captured by existing models.

A unidirectional magnetoresistance observed in bilayer metal films could be used to add directional sensitivity to conventional magnetic sensors based on anisotropic magnetoresistance.

The anomalous Hall effect has been observed in high-quality epitaxial thin films of non-collinear antiferromagnet Mn₃Pt, and can be switched on and off using an electric field.

The fractional quantum Hall effect offers a potential platform to harness non-Abelian anyons. Here, the authors report fractional quantum Hall states in trilayer graphene and drive quantum phase transitions between neighbouring states.

Noncoplanar magnets are promising for spintronics but are rare and challenging to find. Here, the authors provide a chemical design strategy to produce materials with noncoplanar magnetic orders, and strong signatures of their magnetism in the Hall effect.

The topological Hall effect is observed at above room temperature in a bilayer heterostructure composed of thulium iron garnet and platinum, suggesting the formation of skyrmions in a magnetic insulator through the interfacial Dzyaloshinskii–Moriya interaction.

The spin Hall effect induces spin currents in nonmagnetic layers, which can control the magnetization of neighbouring ferromagnets. The transparency of the interface is shown to strongly influence the efficiency of such manipulation.

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.

Andreev reflection is normally known to occur at a metal-superconductor interface. Here, Hashisaka et al. observe an Andreev-like process in a narrow junction between fractional and integer quantum Hall states originating from a topological quantum many-body effect instead of superconductivity.

Non-local transport measurements on mercury telluride quantum wells show clear signatures of the ballistic spin Hall effect. The ballistic nature of the experiment allows the observed effect to be interpreted as a direct consequence of the band structure of these semiconductor nanostructures, rather that being caused by impurity scattering.

The scaling dimension of fractional quantum Hall anyons shows agreement with expectations following examination of thermal-to-shot-noise crossover measurements by fitting to the predicted finite-temperature expression involving both the scaling dimension of quasiparticles and their charge.

A superconductor placed near a quantum Hall edge can show emergent excitations with a range of exotic features. For instance, such heterostructures are predicted to exhibit non-local signatures that are direct extensions of ‘Andreev reflection’.

Energy relaxation crucially impacts transport properties of mesoscopic devices. Here the authors show that energy can be distributed between distant parts of the sample, which may provide a resolution to an outstanding puzzle concerning energy conservation in transport through quantum Hall edges.

Recently, anyonic statistics were observed in collision experiments on fractional quantum Hall states. Here the authors report signatures of anyonic statistics in the integer quantum Hall state with two copropagating channels, where electrons are split into fractional charges by inter-channel interaction.

The authors show that nonlinear self-confinement of magnons in a thick iron garnet film enables magnetic auto-oscillations via local electrical spin injection, resulting in mode-dependent and directional magnon emission in extended magnetic layers.

2D transition metal ditellurides exhibit nontrivial topological phases, but the controlled bottom-up synthesis of these materials is still challenging. Here, the authors report the layer-by-layer growth of large-area bilayer and trilayer 1T’ MoTe2 films, showing thickness-dependent ferroelectricity and nonlinear Hall effect.

Disorder may play a dominant role in determining the nonlinear Hall effect in a topological material. Here, Du et al. derive formulas of the nonlinear Hall conductivity and construct the general scaling law of the nonlinear Hall effect in a tilted two dimensional Dirac model.

Non-Hermitian systems can be described in terms of gain and loss with a coupled environment—a hard feature to tune in quantum devices. Now an experiment shows non-Hermitian topology in a quantum Hall ring without relying on gain and loss.

The nature of the fractional quantum Hall state when the lowest Landau level is half-filled remains controversial. Now, the observation of a topological phase transition at related filling fractions suggests that the half-filled state is non-Abelian.

The superconducting proximity effect has not been experimentally demonstrated in a quantum anomalous Hall insulator. Now this effect is observed in the chiral edge state of a ferromagnetic topological insulator.

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

The nonlinear Hall effect is a quantum phenomenon, in which two perpendicular currents induce a Hall voltage; however, previous theories for this effect has remained at the semi classical level. Here, the authors develop a full quantum theory of the nonlinear Hall effect by using the diagrammatic technique.

Switching of magnetic behaviour is one of the main ideas that drives spintronics. Now, magnetic switching via spin-orbit torque is shown in a moiré bilayer, introducing a platform for spintronic applications.

The nonlinear Hall effect (NLHE) results in a second-harmonic transverse voltage in response to alternating longitudinal current in zero magnetic field and has so far only been observed at low temperatures in bulk materials. Here, the authors observe bulk NLHE at room temperature in the Dirac material BaMnSb₂, which will provide a large photocurrent for applications in THz detection.

Quantum transport of fractional quasiparticles can drastically differ from conventional charge transport. Here the authors demonstrate Andreev-like reflection of a fractional quasiparticle incident on a barrier in the fractional quantum Hall regime.