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Room-temperature nonlinear Hall effect has been observed in wafer-scale (001)-oriented SnTe thin films, enabling wireless, ultrabroadband and low-power rectification at zero electrical bias and zero magnetic field.

The nature of non-saturating magnetoresistance (MR) in topological materials is an important issue in condensed matter research but remains elusive. The authors here report the nonlinear MR at room temperature in WTe₂ with temperature-driven inversion due to the temperature-induced changes in Fermi surface convexity.

Two-dimensional semiconducting transition metal dichalcogenides strongly absorb visible light. Kozawa et al.study the photocarrier relaxation in mono- and bilayer MX2 samples and find that loss of photocarriers by direct recombination becomes a second-order process when excitation is in resonance with band nesting.

Efficient evolution of hydrogen via electrocatalysis at low overpotentials is promising for clean energy production. Monolayered nanosheets of chemically exfoliated WS₂ are shown to be efficient catalysts for hydrogen evolution at very low overpotentials. The enhanced catalytic performance is associated with the high concentration of the strained metallic octahedral phase in the exfoliated nanosheets.

Point defects in 2D semiconductors hold potential as single photon emitters (SPEs), but their controlled fabrication and microscopic understanding remain a challenge. Here, the authors report the synthesis of dilute Nb-doped monolayer WS₂, showing that Nb impurities behave as SPEs with well-defined emission energies.

The layered structure of van der Waals materials leads to highly anisotropic thermal conductivity, due to the van der Waals gap between the layers. Here, Da̧browski et al show how this anisotropic heat transport can be harnessed for ultrafast, optically-induced control of magnetism in Cr₂Ge₂Te₆.

Plasmonic tunnel junctions integrated with a monolayer semiconductor are found to emit photons with energies exceeding the input electrical potential. This peculiar phenomenon is ascribed to being triggered by inelastic electron tunnelling dipoles inducing optically forbidden transitions in the carrier injection electrode.

A significant mobility increase in TMD-based field-effect transistors is achieved via engineering of nanometre-scale corrugations and crests in the dielectric substrate.

The Weyl semimetal WTe₂ possesses strong spin–orbit coupling and time-reversal-protected spin polarization in surface and bulk states. In a WTe₂/permalloy heterostructure, WTe₂ can act as a spin current source that enables magnetization switching at low current densities.

Monolayer MoS₂ can be laterally grown in the vapour–liquid–solid mode, forming highly crystalline nano- and microribbon structures.

Electrostatic gating can be used to modulate the magnetic anisotropy of chromium germanium telluride, a layered ferromagnetic semiconductor, and increase its Curie temperature to 200 K.

Phase engineering of 2D transition metal dichalcogenides enables the investigation of emerging physical properties. Here, the authors report a phase selective in-plane heteroepitaxial method to grow semiconducting H-phase CrSe₂ thin films from MoSe₂ nanoribbons, showing Tomonaga-Luttinger liquid behaviour in the CrSe₂ mirror twin boundaries.

Here, the authors design a microcavity-confined 2D heterojunction to realize the strong coupling among donor exciton, acceptor exciton, and cavity photon mode, leading to an unconventional energy transfer via polariton relaxation with an enhancement factor of ~440.

The recent thrust toward flexible nanoscale devices creates a need for two-dimensional piezoelectric materials. Here, the authors find large piezoelectric response in NbOI₂ flakes ranging from 4 nm to the bulk.

van der Waals magnetic materials, which retain magnetism down to a single two-dimensional layer of atoms, have great technological potential for spin-based information processing, however, typical approaches to measure their spin dynamics are often hampered by the small number of spins in a single atomic layer compared to three dimensional materials. Here, Zollitsch et al present a methodology for the detection of spin dynamics in van der Waals magnets via photon-magnon coupling between it and a superconducting resonator, with potential to resolve spin dynamics down to a single monolayer.

A van der Waals crystal, niobium oxide dichloride, with vanishing interlayer electronic coupling and considerable monolayer-like excitonic behaviour in the bulk, as well as strong and scalable second-order optical nonlinearity, is discovered, which enables a high-performance quantum light source.

Strained NbOI₂ flakes with a thickness of 20 nm exhibit a record SHG absolute conversion efficiency of >0.2% and an effective bulk-like nonlinear susceptibility of 1.1 × 10⁻⁹ m V⁻¹ at the fundamental wavelength of 1,050 nm. The spatial profile of the polarized second-harmonic generation response can be tuned by the fundamental wavelength.

Lattice distortions induced by ripples in two-dimensional molybdenum disulfide can reduce electron–phonon scattering, leading to improved charge carrier mobility and enhanced transistor performance.

Insulating molecular layers on the basal plane of 2D perovskite is a major bottleneck for charge injection that limiting device performance. Here, the authors show that plane-contacted graphene functions as a low barrier and gate-tunable contact to overcome this limitation.

Van der Waals magnetic materials, which maintain their magnetic ordering down to a monolayer have been found to host a variety of spin textures, including topological spin textures such as skyrmions. Here, Khela et al. demonstrate laser induced topological switching, between skyrmions, anti-skyrmions and stripe domains in CrGeTe₃.

Two-dimensional materials have excellent electrical properties, but poor luminescence limits their application in optoelectronics. Here, the authors demonstrate a plasmon-induced 20,000-fold enhancement in photoluminescence from tungsten diselenide suspended across a nanometre-scale gap.

Atomically thin transition metal dichalcogenides can be grown on large scale using chemical vapour deposition which, however, determines presence of grain boundaries. Here, the authors report that third-harmonic generation imaging provides excellent sensitivity and fast speed for grain boundary visualization in MoS₂.

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.

Reversible structural surface relaxation under laser exposure is observed for monolayers of 2D metal halide perovskites. These structural changes also induce reversible shifts in the photoluminescence peaks of these materials.

Substitutional doping is well-established in traditional semiconductors but has not been extensively explored in two-dimensional semiconductors. Here, the authors investigate the structural and electronic effects of Nb doping in MoS₂ crystals.

Atomically thin transition metal dichalcogenides offer a platform to explore the valley degree of freedom originating from their electronic band structure. Here, the authors use polarization- and time-resolved spectroscopy to investigate the temperature-dependent valley pseudospin relaxation processes in WSe₂ monolayers.

Chemically derived graphene oxide (GO) has recently moved on from simply being a graphene precursor to attracting interest for its own properties. This Review discusses how the presence of oxygenated groups and domains of sp²- and sp³-hybridized carbons makes GO tunable and promising for various physical and biological applications.

Quantum light-emitting devices (QLEDs) are essential for scalable on-chip quantum technologies. This Perspective analyses electrical pumping and quantum confinement schemes enabled by van der Waals materials and explores how they can be harnessed for the advancement of QLED development.

Broken inversion symmetry in a type-II Weyl semimetal TaIrTe₄ enables observation of the room-temperature nonlinear Hall effect as well as wireless radiofrequency rectification.

Two-dimensional materials have recently garnered much interest in the scientific and technology communities. This Review describes how ultrathin transition metal dichalcogenides combine tunable structure and electronic properties, achieved through altering their composition, with versatile chemistry. This makes them attractive in various fields, for example as lithium-ion battery electrodes and electrocatalysts for the hydrogen evolution reaction.