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The unusual electronic properties of graphene can be modified by placing it on a boron-nitride substrate with a small crystallographic alignment angle. Chen et al.now reveal that such heterostructures grown by epitaxy have a large bandgap, useful for applications using magneto-optical spectroscopy.

Layered materials governed by van der Waals (vdW) interactions offer opportunities for interlayer tuning of the materials' properties. Here, the authors demonstrate that in-plane tensile strain can effectively tune the vdW interactions of few-layered black phosphorus and weaken its interlayer coupling even though the sample shrinks in the vertical direction.

Researchers clarify damping pathways for mid-infrared graphene plasmons, including graphene intrinsic optical phonons and edge scattering. They also demonstrate the guiding of mid-infrared graphene plasmons in 50-nm-wide structures with an electromagnetic mode area of 10⁻³μm² and a propagation length of 200 nm.

Multi-dimensional detection of optical information with a single device enables energy- and area-efficient sensing capabilities. Here, the authors report dual-band infrared detectors based on misaligned 2D black phosphorus and black arsenic phosphorus, sensitive to light intensity, spectrum and polarization.

Integrated polarization-sensitive photodetectors are important for sensing applications and optical communication. Here, the authors report the realization of 2D black phosphorus homojunction photodetectors defined by ferroelectric substrates, showing polarization ratios up to 288 and high responsivity in the near-infrared.

Plasmons are combinations of light and collective electron oscillations. The demonstration that plasmons can be dragged by drifting electrons in the 2D material graphene could lead to advances in optical physics.

Single-crystal black phosphorus nanoribbons are grown uniformly on insulating substrates by chemical vapour transport growth with black phosphorus nanoparticles as seeds, demonstrating potential for application in nanoelectronic devices and the exploration of the exotic physics in black phosphorus.

How the carriers behave in a Weyl semimetal if they occupy the lowest Landau level remains elusive. Here, the authors report evidences of electrons occupying zeroth chiral Landau levels with distinct linear dispersion behaviors for two inequivalent Weyl nodes in a Weyl semimetal NbAs.

Anisotropic light-matter excitations in van der Waals materials are expected to have an impact on nanophotonics applications. Here, the authors report the observation of canalized in-plane mid-infrared plasmons in the semimetallic phase of WS₂ and demonstrate their electrical tunability via ion intercalation.

Unique electronmagnetic response of Weyl semimetals have only been reported in static field regime. Here, the authors report evidence of a dynamical chiral anomaly response realized by internal collective lattice deformation with an external static magnetic field in a Weyl semimetal NbAs.

The resonant frequency and magnitude of graphene plasmons in graphene/insulator stacks depend on the layer number, which allows tunable filters and polarizers to be built.

Naturally occurring hyperbolic polaritons exist in a class of layered materials. Here, the authors show evidence, via optical spectroscopy, of hyperbolic exciton-polaritons in phosphorene, originating from its in-plane anisotropy and strong exciton resonances.

Here, the authors determine the exciton polarizabilities for 3- to 11-layer black phosphorus via frequency-resolved photocurrent measurements on dual-gate devices, and unveil the exciton response for higher-index sub-bands under the gate electrical field, as well as a carrier screening effect in thicker samples.

In-plane hyperbolic phonon polaritons in α-MoO₃ crystals hold promise for terahertz (THz) and longwave infrared (LWIR) photonic applications, but their coupling with far-field excitations remains challenging. Here, the authors report the fabrication of α-MoO₃ ribbon arrays that can be applied as tunable THz and LWIR filters and polarizers.

Few-layered black phosphorus offers an infrared bandgap, complementing that of graphene and transition metal dichalcogenides. Here, the authors investigate the thickness- and strain-dependent electronic structure of black phosphorus using polarised infrared spectroscopy.

By patterning graphene with sub-wavelength features to introduce plasmonic modes, its optical properties can be tailored. Freitag et al. show how tunable plasmons in graphene nanoribbons can be exploited to form polarization-sensitive graphene photodetectors in the mid-infrared spectral region.

Rapid growth of highly crystalline Covalent organic framework (COF) materials remains challenging. Here, the authors accelerate single-crystal polymerization using supercritical CO2 and realize the fabrication of two-dimensional COF single crystals within several minutes.

Here, arrays of 2H-TaSe2 nanoribbons are shown to exhibit a broadband plasmonic response that can be tuned from THz to telecom range. These localized plasmons can also couple to charge density wave excitations, offering insights on the physics of plasmonic excitations in 2D correlated materials.

For many two-dimensional semiconductors, such as MoS₂, the exciton absorption increases with thickness. Here, the authors show that, in black phosphorus, less material absorbs more light due to exciton resonances.

Hyperbolic plasmonic surfaces supporting highly directional propagating plasmon-polaritons have been realized in artificial metamaterials. Here, the authors demonstrate experimentally a hyperbolic plasmonic surface naturally occurring in thin films of WTe2, a type-II Weyl semimetal with layered structure.

ZrTe₅ has attracted intensive research interests because of the potential topological property. Here based on the transports and optic experiments, we observe unusual Landau quantization, non-trivial Berry phase and highly anisotropic carrier mass, which reveals quasi-two-dimensional Dirac fermions in bulk ZrTe₅. The system is understood as locating at the critical point between a three-dimensional (3D) Dirac semimetal and a topological insulator. New physics or device application can be possibly realized in this quasi-2D ultra-relativistic system beyond graphene.