Antiferromagnets display enormous potential in spintronics owing to its intrinsic nature, including terahertz resonance 1,2 , multilevel states 3,4 , and absence of stray fields 5,6 . Combining with the layered nature, van der Waals (vdW) antiferromagnets hold the promise in providing new insights and new designs in twodimensional (2D) spintronics. The zero net magnetic moments of vdW antiferromagnets strengthens the spin stability, however, impedes the correlation between spin and other excitation elements, like excitons 7,8 . Such coupling is urgently anticipated for fundamental magneto-optical studies and potential opto-spintronic devices. Here, we report an ultra-sharp excitonic emission with excellent monochromaticity in antiferromagnetic nickel phosphorus trisulfides (NiPS3) from bulk to atomically thin flakes. We prove that the linear polarization of the excitonic

Two-dimensional nanoelectronics, plasmonics, and emergent phases require clean and local charge control, calling for layered, crystalline acceptors or donors. Our Raman, photovoltage, and electrical conductance measurements combined with ab initio calculations establish the large work function and narrow bands of α-RuCl 3 enable modulation doping of exfoliated single and bilayer graphene, chemical vapor deposition grown graphene and WSe 2 , and molecular beam epitaxy grown EuS. We further demonstrate proof of principle photovoltage devices, control via twist angle, and charge transfer through hexagonal boron nitride. Short-ranged lateral doping (≤65 nm) and high homogeneity are achieved in proximate materials with a single layer of α-RuCl 3 . This leads to the best-reported monolayer graphene mobilities (4900 cm 2 /(V s)) at these high hole densities (3 × 10 13 cm −2 ) and yields larger charge transfer to bilayer graphene (6 × 10 13 cm −2 ).

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MXenes are emerging 2D materials with intriguing properties such as excellent stability and high conductivity. Here, a systematic study on the Raman spectra of 2D α‐Mo2C (molybdenum carbide), a promising member in MXene family, is conducted. Six experimentally observed Raman modes from ultrathin α‐Mo2C crystal are first assigned with the assistance of phonon dispersion calculated from density functional theory. Angle‐resolved polarized Raman spectroscopy indicates the anisotropy of α‐Mo2C in the b–c plane. Raman spectroscopy is further used to study the unique domain structures of 2D α‐Mo2C crystals grown by chemical vapor deposition. A Raman mapping investigation suggests that most of the α‐Mo2C flakes contain multiple domains and the c‐axes of neighboring domains tend to form a 60° or 120° angle, due to the weak MoC bonds in this interstitial carbide and the low formation energy of the carbon chains along three equivalent directions. This study demonstrates that polarized Raman spectroscopy is a powerful and effective way to characterize the domain structures in α‐Mo2C, which will facilitate the further exploration of the domain‐structure‐related properties and potential applications of α‐Mo2C.

Graphene is a two-dimensional (2D) material consisting of a single sheet of sp2 hybridized carbon atoms laced in a hexagonal lattice, with potentially wide usage as a Raman enhancement substrate, also termed graphene-enhanced Raman scattering (GERS), making it ideal for sensing applications. GERS improves upon traditional surface-enhanced Raman scattering (SERS), combining its single-molecule sensitivity and spectral fingerprinting of molecules, and graphene’s simple processing and superior uniformity. This enables fast and highly sensitive detection of a wide variety of analytes. Accordingly, GERS has been investigated for a wide variety of sensing applications, including chemical- and bio-sensing. As a derivative of GERS, the use of two-dimensional materials other than graphene for Raman enhancement has emerged, which possess remarkably interesting properties and potential wider applications in combination with GERS. In this review, we first introduce various types of 2D materials, including graphene, MoS2, doped graphene, their properties, and synthesis. Then, we describe the principles of GERS and comprehensively explain how the GERS enhancement factors are influenced by molecular and 2D material properties. In the last section, we discuss the application of GERS in chemical- and bio-sensing, and the prospects of such a novel sensing method.