The intrinsic in-plane isotropy of high-symmetry two-dimensional (2D) transition metal dichalcogenides (TMDs) limits their applicability in polarization-sensitive optoelectronic devices. Conventional strategies such as heterointerface and strain engineering can break rotational symmetry and induce anisotropy, yet they suffer from lattice-matching constraints and limited strain tunability. Here, we present a dual-modulation approach that integrates bilayer WS₂ with the anisotropic van der Waals crystal CrOCl and applies externally engineered hole-induced stress. The in-plane lattice anisotropy of CrOCl induces interfacial symmetry breaking in WS₂, while hole geometry generates controllable stress gradients. This synergy yields a pronounced optical anisotropy, with excitonic linear polarization reaching up to 59%. Furthermore, external magnetic fields can effectively modulate exciton anisotropy, whereas the anisotropy remains stable across various temperatures. First-principles calculations reveal that interfacial charge redistribution, induced by lattice distortion, underlies the observed optical anisotropy. Our results demonstrate a multi-field tuning platform—mechanical, magnetic, and thermal—for tailoring anisotropic light-matter interactions in 2D semiconductors, advancing the development of next-generation directional optoelectronic and quantum devices.

The magnetic proximity effect enables interfacial modulation of excitonic and spin-valley properties in transition metal dichalcogenides (TMDs), offering a versatile route toward next-generation spintronic and valleytronic devices. However, the inherently weak photoluminescence (PL) of bright excitons—suppressed by proximity-induced darkening mechanisms—hinders the optical detection of magnetic interactions. Here, we demonstrate substantial exciton emission enhancement in CrOCl/WSe₂ (HS) and twisted 90°-CrOCl/CrOCl/WSe₂ (THS) heterostructures by employing plasmonic Au nanopillar arrays to activate surface plasmon polariton (SPP) coupling. The neutral exciton emission intensity is enhanced by factors of 5 and 18 for HS/Au and THS/Au, respectively, with enhancements persisting under high magnetic fields and elevated temperatures (~ 10-fold in THS/Au). Enabled by this amplification, we observe pronounced Zeeman splitting and modified intervalley relaxation pathways, indicating significant magnetic proximity interactions. Finite-element simulations and first-principles calculations reveal that the enhancement arises from local electromagnetic field concentration and layer-dependent interfacial coupling. Our results establish SPP-assisted PL enhancement as an effective strategy for probing weak magneto-optical signatures, paving the way for detailed exploration of exciton–magnon coupling and interface-driven quantum phenomena in two-dimensional (2D) magnetic heterostructures.

Moiré superlattices in twisted two-dimensional (2D) van der Waals materials offer a versatile platform for engineering quantum states, leading to breakthroughs in correlated insulating phases, superconductivity, and flat-band physics. In particular, the Moiré potential in twisted transition metal dichalcogenides (TMDs) can trap excitons and trions, resulting in quantized energy levels and emergent many-body interactions. However, methods for precisely modulating excitonic complexes in these systems remain insufficiently explored. Here, we fabricate 1.3°-twisted R-stacked MoSe₂ homobilayers on prepatterned substrates and investigate strain-engineered Moiré trions using spectroscopic techniques at variable temperatures and magnetic fields. In strained twisted MoSe₂, we observe a significant increase in Moiré trion emission multiplicity, accompanied by a 65% reduction in linewidth. Raman spectroscopy, second-harmonic generation (SHG) analysis, and density functional theory (DFT) calculations reveal that the enhanced splitting and localization of Moiré trion emissions are due to broken symmetry and stronger lattice reconfiguration induced by uniaxial strain, which lifts the degeneracy of flat bands and spatially confines the Moiré potential. This work advances the understanding of strain-coupled Moiré physics and paves the way for developing quantum light sources and information devices based on Moiré superlattices.

Van der Waals heterostructures are emerging as a versatile platform for next-generation electronic and photonic devices due to their unique anisotropic properties. While extensive studies have addressed symmetry breaking in transition metal dichalcogenides (TMDCs), the influence of magnetic fields on optical anisotropy remains underexplored. Here, we present an isotropic/magnetic/anisotropic heterostructure composed of WSe₂, ReSe₂, and the magnetic material CrOCl, which induces in-plane anisotropy in monolayer WSe₂. Density functional theory (DFT) calculations reveal significant modulation of the in-plane charge density of WSe₂ by ReSe₂ and CrOCl, providing direct evidence of anisotropic electronic behavior. Photoluminescence measurements at 300 and 1.7 K show strongly linearly polarized exciton emission, with magnetic fields ranging from −9 to 9 T modulating the anisotropy. Specifically, the anisotropy is enhanced by up to 28.34% and reduced by 40.37% under different magnetic field directions. Temperature variations also influence the linear polarization, achieving anisotropy ratios of 2.34 for neutral excitons and 1.77 for charged excitons. These results underscore a robust approach to dynamically tuning optical anisotropy via magnetic and thermal controls, paving the way for advanced polarization-sensitive optoelectronic applications.

van der Waals (vdW) heterostructures, composed of stacked materials with varying symmetries, offer exceptional opportunities in electronics and optics due to their unique anisotropic properties. However, the influence of low-symmetry layer thickness on modulating anisotropic optical responses remains elusive. Here, we fabricate heterostructures by combining monolayer (1L) MoS₂ with ReS₂ layers of varying thickness, uncovering tunable optical anisotropy. The degree of excitonic line polarization increases with ReS₂ thickness, reaching saturation due to lattice relaxation at the heterostructure interface. Density functional (DFT) theory calculations confirm that the lattice reconstruction of MoS₂ is influenced by the number of low-symmetry ReS₂ layers, providing direct evidence of interlayer coupling effects. Remarkably, we observe anisotropy ratios as high as 2.01 and 2.12 for charged and neutral excitons, respectively, underscoring robust anisotropic optical behavior. Additionally, we demonstrate that external magnetic fields can effectively modulate this anisotropy, whereas temperature variations have a negligible impact on line polarization. These findings advance our understanding of the interplay between thickness, symmetry, and external stimuli in heterostructures, paving the way for designing advanced optical devices with precise polarization control.

Atomically thin two-dimensional (2D) magnetic materials offer unique opportunities to enhance interactions between electron spin, charge, and lattice, leading to novel physical properties at low-dimensional scales. While extensive research has explored how breaking three-fold (C₃) rotational symmetry in transition metal dichalcogenides (TMDC) can induce optical anisotropy at heterointerfaces, the role of magnetism in modulating these anisotropic optical properties remains underexplored. Here, we engineer an antiferromagnet/semiconductor heterostructure by coupling isotropic MoWSe₂ with the low-symmetric antiferromagnet NiPS₃, introducing in-plane anisotropy in the MoWSe₂ alloy. Low-temperature photoluminescence (PL) measurements reveal a pronounced linear polarization-dependent exciton emission intensity at the MoWSe₂/NiPS₃ interface, with anisotropy ratios of 1.09 and 1.07 for charged and neutral excitons, respectively. Furthermore, applying an out-of-plane magnetic field results in a dramatic rotation of the exciton polarization direction by up to 90° at 9 T, significantly exceeding the previously reported maximum deflection of around 27°. This pronounced polarization rotation is not solely attributed to valley coherence, indicating a strong influence of the magnetic order in NiPS₃. These findings provide new insights into the role of magnetic ordering in tuning optical anisotropy in 2D materials, paving the way for the development of advanced polarization-sensitive optoelectronic and magneto-optic devices.

Dark excitons in group VI transition metal dichalcogenides (TMDCs) have garnered significant interest due to their extended charge lifetime, spin lifetime, and diffusion length compared to bright excitons, presenting exciting opportunities for quantum communication and optoelectronic devices. However, their optical insensitivity poses challenges for investigation and manipulation. Here, we employ a strain engineering approach to introduce localized strain in monolayer WSe₂ using a substrate with prepatterned holes, resulting in the hybridization of dark excitons with bright defect states. This hybridization significantly enhances photoluminescence (PL) intensity and reduces the linewidths of dark excitons by orders of magnitude. Additionally, the hybridized states exhibit unique features in temperature-dependent and linearly polarized PL spectra, with stable localization across a broad excitation power range (up to 0.4 mW) and tunable circular polarization under a magnetic field (87% at −9 T). These findings underscore strain engineering as an effective method for enhancing dark excitons and provide new insights into exciton physics in TMDCs, paving the way for advanced optoelectronic technologies.

Moiré superlattices based on twisted transition metal dichalcogenide (TMD) heterostructures have recently emerged as a promising platform for probing novel and distinctive electronic phenomena in two-dimensional (2D) materials. By stacking TMD monolayers with a small twist angle, these superlattices create a periodic modulation of the electronic density of states, leading to the formation of mini bands. These mini bands can exhibit intriguing properties such as flat bands, correlated electron behavior, and unconventional superconductivity. This review provides a comprehensive overview of recent progress in Moiré superlattices formed from twisted TMD heterostructures. It covers the theoretical principles and experimental techniques for creating and studying these superlattices, and explores their potential applications in optoelectronics, quantum computing, and energy harvesting. The review also addresses key challenges, such as improving the scalability and reproducibility of the fabrication process, emphasizing the exciting opportunities and ongoing hurdles in this rapidly evolving field.

Pressure exerts a profound influence on atomic configurations and interlayer interactions, thereby modulating the electronic and structural properties of materials. While high pressure has been observed to induce a structural phase transition in bulk PdSe₂ crystals, leading to a transition from semiconductor to metal, the high-pressure behavior of few-layer PdSe₂ remains elusive. Here, employing diamond anvil cell (DAC) techniques and high-pressure Raman spectroscopy, we investigate the structural evolution of layer-dependent PdSe₂ under high pressure. We reveal that pressure significantly enhances interlayer coupling in PdSe₂, driving structural phase transitions from an orthorhombic to a cubic phase. We demonstrate that PdSe₂ crystals exhibit distinct layer-dependent pressure thresholds during the phase transition, with the decrease of transition pressure as the thickness of PdSe₂ increases. Furthermore, our results of polarized Raman spectra confirm a reduction in material anisotropy with increasing pressure. This study offers crucial insights into the structural evolution of layer-dependent van der Waals materials under pressure, advancing our understanding of their pressure-induced behaviors.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have garnered considerable attention for their promising applications in sensors and optoelectronic devices, owing to their exceptional optical, electronic, and optoelectronic properties. However, the inherent high symmetry of TMD lattices imposes limitations on their functional versatility. Here, we present a strategy to disrupt the C₃ rotational symmetry of monolayer WSe₂ by fabricating a heterostructure incorporating WSe₂ and SiP flakes. Through comprehensive experimental investigations and first-principle calculations, we elucidate that in the WSe₂/SiP heterostructure, excitons—both neutral and charged—emanating from WSe₂ exhibit pronounced anisotropy, which remains robust against temperature variations. Notably, we observe an anisotropic ratio reaching up to 1.5, indicating a substantial degree of anisotropy. Furthermore, we demonstrate the tunability of exciton anisotropy through the application of a magnetic field, resulting in a significant reduction in the anisotropic ratio with increasing field strength, from 1.57 to 1.18. Remarkably, the change in heterojunction anisotropy ratio reaches 24.8% as the magnetic field increases. Our findings elucidate that the perturbation of the C₃ rotational symmetry of the WSe₂ monolayer arises from a non-uniform charge density distribution within the layer, exhibiting mirror symmetry. These results underscore the potential of heterostructure engineering in tailoring the properties of isotropic materials and provide a promising avenue for advancing the application of anisotropic devices across various fields.