Bi1.3In0.7Se3 nanowire, whose band gap has been opened by doping, falls short of expectations in a broad-spectrum photodetector, raising suspicions that optoelectronic energy is being dissipated in the form of phonons. This work proves that a coherent phonon-generated oscillatory signal at approximately 1.29 GHz is responsible for approximately 46.9% of the total energy loss. The Auger recombination is introduced to suppress such oscillations, and by constructing 1D/2D heterojunctions, photogenerated carriers are transferred to the 2D material WSe2. After that, the light response from ultraviolet to near-infrared is enhanced, with the visible band specifically increasing 35.6%. The key mechanism is the interlayer electric field, generated by charge transfer, whose effectiveness is validated by the signal amplification and a 64 meV blueshift of the WSe2 B exciton. This study provides a practical way to minimize coherent phonon oscillation and boost efficiency through carrier transfer, enhancing the device’s detection efficiency by nearly 10-fold.

The dynamic control of light polarization is essential for advanced photonic technologies, yet remains challenging to achieve in a compact format. In this work, we introduce a novel grating-waveguide-grating platform that harnesses degenerate bound states in the continuum (BIC) and resonances to enable fully tunable polarization conversion. A key innovation lies in the dual-mode coupling mechanism: degenerate BIC-resonance modes not only exhibit ultrahigh quality factors but also support enhanced interaction with external excitations. This dual mode dramatically amplifies the magneto-optical effect and allows active polarization manipulation, including linear, elliptical, left-and right-handed circular polarization states via symmetry breaking induced by grating displacement or an external magnetic field. This mechanism offers a compact platform for polarization-resolved imaging, tunable photonic devices, and optical sensing.

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 degrees- 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 (similar to 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 twodimensional (2D) magnetic heterostructures.

ABSTRACT Programmable spatial control of excitonic quasiparticles is essential for realizing integrated photonic and information‐encoding platforms based on van der Waals heterostructures. A common strategy is electrostatic gating, which switches ferroelectric polarization and modulates excitonic responses through carrier doping and field effects. However, electrically driven polarization control requires additional electrodes and repeated voltage cycling, which may introduce charge trapping, polarization fatigue, and long‐term reliability constraints, complicating device integration and scalability. Here, we demonstrate flexoelectrically assisted exciton patterning by integrating MoSe 2 /CuInP 2 S 6 heterostructures onto periodic Au stripe arrays. Atomic force microscopy and Piezoresponse force microscopy reveal a periodic ferroelectric‐domain texture that closely follows the imposed surface Au stripe arrays corrugation. Meanwhile, a reduced‐order curvature‐based calculation analysis captures the periodic through‐thickness bending‐strain gradient and the associated flexoelectric polarization preference. The resulting ferroelectric landscape creates a domain‐dependent electrostatic environment in the adjacent MoSe 2 , producing a spatial redistribution of neutral exciton and trion emission together with modulation of their valley‐polarized response. By linking microscale deformation, flexoelectrically assisted ferroelectric‐domain patterning, and local excitonic behavior, this work establishes a scalable, fabrication‐defined route toward artificial excitonic lattices and spatially encoded optoelectronic architectures.

Valley pseudospin, the third quantum degree of freedom for electrons in two-dimensional crystals after charge and spin, exhibits two distinguishable states (K and -K) and serves as a versatile platform for information encoding, manipulation, and low-power quantum technologies. However, most existing approaches rely on continuous external fields to transiently induce valley polarization, without stable K/-K occupation imbalance, fundamentally preventing nonvolatile valley-based memory. Here, we demonstrate nonvolatile and electrically programmable control of valley pseudospins in a van der Waals heterostructure composed of monolayer MoSe2 and ferroelectric CuInP2S6 (CIPS). By integrating a gold micropillar electrode array with an electromechanical modulation scheme, localized strain gradients are introduced into the MoSe2/CIPS heterostructure, giving rise to flexoelectric fields that regulate Cu+ redistribution and enable robust, energy-efficient control of excitonic properties. Magneto-optical spectroscopy reveals that ferroelectric polarization-induced interfacial fields enable reversible switching between spin-allowed bright and spin-forbidden dark trions, accompanied by a reversible Land & eacute; g-factor tuning from -4.7 to -7.8. Under an external magnetic field, electrically driven valley polarization reaches 35.7%, exhibiting high contrast and long-term retention. Furthermore, ASCII-encoded valley polarization states demonstrate reliable nonvolatile information storage. This work establishes a versatile ferroelectric platform for reconfigurable valleytronic memory and programmable quantum photonics, paving the way toward scalable and energy-efficient quantum information technologies.

Magnetic proximity effects in van der Waals heterostructures provide an optical route to manipulate valley pseudospins in transition-metal dichalcogenides, but abrupt switching of two-dimensional (2D) ferromagnets (FM) limits continuous valley modulation. We demonstrate that the proximity-induced valley response of WSe2 can be modified by engineering the interfacial magnetic environment in WSe2-CrBr3-CrPS4 heterostructures. Circularly polarized magneto-photoluminescence reveals robust nonvolatile valley polarization in WSe2-CrBr3 with a pronounced low-field hysteresis tracking CrBr3 magnetization. Spectroscopy and calculations indicate that spin-selective interfacial charge transfer and orbital hybridization enhance the proximity exchange field and valley Zeeman splitting. Introducing antiferromagnetic (AFM) CrPS4 weakens the degree of circular polarization modulation and broadens the low-field valley polarization reversal, consistent with an interfacial AFM/FM exchange pinning scenario. These results show that interfacial magnetic engineering can tailor proximity-induced valley responses in 2D heterostructures.

Moiré excitons in twisted transition metal dichalcogenides form a highly tunable and strong correlated system with controllable valley pseudospins offering a promising quantum platform for valleytronics. However, due to inherent magnetic moment, their valley characteristics are fixed and exhibit weak response to external perturbations, limiting their application in spintronics and valleytronics. Here, we manipulate the valley polarization and valley splitting of moiré exciton utilizing magnetic proximity effect through constructing van der Waals heterostructure consisting of twisted WSe2 homobilayers and ferromagnetic 1T-VSe2. Photoluminescence measurements reveal that interfacial coupling deepens the moiré potential by ∼18% (from 45.33 to 53.57 meV). Furthermore, the magnetic proximity effect breaks the time-reversal symmetry in twisted WSe2, producing a zero-field valley splitting of ∼0.9 meV, corresponding to an effective magnetic field of ∼1.71 T. This coupling increases the Landé g-factor of moiré excitons and enhances the magnetic-filed response of their valley polarization by approximately 200% and 300%, respectively. Temperature-dependent measurements further reveal that the thermal evolution of valley polarization is governed by the spin thermodynamics of the ferromagnetic layer, marked by its sharp decrease with rising temperature. These findings establish the magnetic proximity modulation as a powerful and deterministic strategies to control valley pseudospins on a moiré exciton, paving the way for the development of valleytronics and quantum spin devices.

van der Waals heterostructures integrating two-dimensional magnets with transition-metal dichalcogenides provide a promising platform for controlling coupled spin and valley physics, yet the origin of magnetically induced valley polarization remains unresolved. Here we show that interfacial magnetic order governs valley exciton dynamics in WS2/Fe3GaTe2 heterostructures. By comparing bottom- and top-stacked architectures, we disentangle intrinsic magnetic proximity effects from oxidation-driven interfacial reconstruction. The protected bottom-stacked interface preserves ferromagnetic order, yielding pronounced valley hysteresis and a giant valley exciton Zeeman splitting of 13.7 meV, equivalent to an effective magnetic field of ∼59 T. In contrast, the exposed top-stacked interface exhibits only 1.26 meV splitting. Polarization-resolved photoluminescence, high-field magneto-optical measurements, and first-principles calculations reveal that oxidation induces an interfacial transition from ferromagnetic to antiferromagnetic order, suppressing the proximity exchange field through weakened Fe-W orbital hybridization. These results establish interfacial magnetic reconstruction as the key factor governing magneto-valley coupling.

Two-dimensional (2D) perovskites are widely introduced into formamidinium (FA+) based three-dimensional (3D) perovskites due to their major benefits of: (i) stabilizing the α-phase of FA+-based perovskites; (ii) regulating the crystallization process; (iii) mitigating interface defects. However, knowledge regarding how the configuration of bulky ammonium cations influences the formation and performance of 2D/3D heterogeneous structures are still scarce. Here, we report that substituting phenethylammonium with methoxyl (MeO-PEA+) can decrease its solubility in polar solvents and enhance the α-phase stability for both the FA-based perovskite crystallization nuclei and final polycrystalline films. Adding a minimal concentration (0.3%) of p-methoxyphenethylammonium chloride (MeO-PEACl) in the perovskite precursor can achieve both a grain boundary wrapping and an in situ formation of buried 2D/3D perovskite structures, leading to solar cells with increased open-circuit voltage from 1.11 to 1.16 V and power conversion efficiency (PCE) from 21.1% to 23.1%. The resulting 2D/3D heterogeneous film can maintain its black phase after 3380 h of exposure at 65 ± 10% relative humidity, and the corresponding solar cells preserved 98% of their initial PCE after 1850 h of heating at 65°C.

Photodetectors underpin optical imaging, communication, and emerging photonic technologies. However, most devices are limited to intensity detection and underutilize the polarization degree of freedom, which is vital for feature discrimination and high-density information encoding. Herein, we introduce symmetry breaking by integrating double rotational symmetry CrOCl with triple rotational symmetry PtS2 to construct a PtS2/CrOCl van der Waals heterostructure. The crystal symmetry contrast enhances interfacial anisotropic states, while localized holes in CrOCl and high-mobility electrons in PtS2 create intrinsic spatial charge separation that suppresses carrier recombination. Consequently, the device achieves a high responsivity of 25.9 A W-1 and an external quantum efficiency of 7942%. Benefiting from lattice-anisotropy-photon coupling, the PtS2/CrOCl heterostructure exhibits strong polarization sensitivity across a broad spectral range from 405 to 1064 nm, with an anisotropy ratio up to ∼8. This performance supports polarization-resolved single-pixel imaging and near-infrared polarized optical communication. Our results demonstrate that symmetry-breaking-induced anisotropy engineering provides a powerful strategy for high-performance, broadband, and polarization-sensitive photodetection, offering promising opportunities for next-generation photonic information technologies.

Magnetic proximity effects in van der Waals heterostructures provide an optical route to manipulate valley pseudospins in transition-metal dichalcogenides, but abrupt switching of two-dimensional (2D) ferromagnets (FM) limits continuous valley modulation. We demonstrate that the proximity-induced valley response of WSe2 can be modified by engineering the interfacial magnetic environment in WSe2-CrBr3-CrPS4 heterostructures. Circularly polarized magneto-photoluminescence reveals robust nonvolatile valley polarization in WSe2-CrBr3 with a pronounced low-field hysteresis tracking CrBr3 magnetization. Spectroscopy and calculations indicate that spin-selective interfacial charge transfer and orbital hybridization enhance the proximity exchange field and valley Zeeman splitting. Introducing antiferromagnetic (AFM) CrPS4 weakens the degree of circular polarization modulation and broadens the low-field valley polarization reversal, consistent with an interfacial AFM/FM exchange pinning scenario. These results show that interfacial magnetic engineering can tailor proximity-induced valley responses in 2D heterostructures

Moiré superlattices have emerged as a powerful platform for engineering quantum materials, where lattice mismatch modifies electronic structures to produce flat minibands and novel correlated states, including insulating phases and topological excitons. However, achieving spatially precise control over the moiré potential and symmetry remains elusive. This study demonstrates a strain modulation strategy based on patterned gold grating substrates, enabling spatially controlled exciton localization in 3.6° twisted WSe2 homobilayers. Under this engineered strain, the moiré exciton emission peak exhibits enhanced splitting, a remarkable 43% reduction in spectral linewidth, and substantially enhanced luminescence intensity. Temperature-dependent photoluminescence (PL) measurements reveal that strain-deepened moiré potential effectively suppresses exciton dissociation. Furthermore, circularly polarized PL under applied magnetic fields shows strain-enhanced Zeeman splitting and a threefold increase in the slope of valley polarization versus magnetic field. First-principles calculations confirm that the strain-mediated band structure modification and charge redistribution collectively enhance the localization effects. These findings establish a robust approach for precisely manipulating moiré excitons and pave a pathway for exploring strongly correlated quantum states.

Platinum diselenide (PtSe2) exhibits a distinctive thickness-modulated metal-to-semiconductor transition, which makes it suitable for diverse applications in nanoelectronics and optoelectronics. This study systematically investigates the spatiotemporal dynamics of photoexcited carrier relaxation in PtSe2. Through temperature-dependent ultrafast spectroscopy, two distinct low-frequency acoustic phonons (AP) were identified in multilayer PtSe2. Transient absorption microscopy (TAM) measurements reveal thickness-dependent relaxation dynamics and distinct carrier diffusion behavior in multilayer PtSe2. These findings indicate superior carrier transport properties, with a measured mobility of 394.1±38.5 cm2·V−1·s−1 for multilayers. Temperature-dependent ultrafast dynamics, acquired using a custom-built cryogenic pump-probe system, reveal two coherent AP modes, ω1 and ω2, with central frequencies of 1.27 and 0.17 THz, respectively. The higher frequency ω1 mode corresponds to shear mode with a nominal electron-phonon coupling constant λω1 = 2.22. To our knowledge, this study represents a pioneering investigation that employs low-temperature ultrafast spectroscopy to elucidate the AP mode and strong electron-phonon coupling in semimetallic PtSe2 systems. These findings offer fundamental insights into the semimetallic nature of PtSe2 and establish a basis for designing ultrafast photonic devices that harness its distinct optoelectronic response.

Precise manipulation and directed transport of micro- and nano-particles are cornerstones of emerging lab-on-a-chip technologies. Traditional optofluidic systems that combine optical tweezers with microfluidic channels enable long-range transport. However, they rely on fixed physical boundaries that lack reconfigurability. To bridge this gap, we propose a reconfigurable virtual optical waveguide (VOW) based on a discretized beam-shaping strategy. By superposing two orthogonally polarized shaped beams, we construct interference-free optical channels without physical boundaries. This platform enables programmable transport along complex trajectories, including space-filling Hilbert curves that maximize interaction path length, and shields the transport channel from perturbations induced by surrounding particles. Crucially, the VOW offers multi-dimensional sorting capabilities: (i) it performs precise size-dependent sieving via tunable channel widths, and (ii) it functions as an intrinsic material filter by stably guiding scattering-dominated particles (e.g., gold) while rejecting gradient-dominated dielectric ones. This work establishes a versatile, contactless strategy for adaptive optical logistics and on-chip material purification.

ABSTRACT Interlayer excitons in transition‐metal dichalcogenide (TMD) van der Waals heterostructures offer long lifetimes, out‐of‐plane dipoles, and valley‐selective optical selection rules. However, active and energy‐efficient control of their formation and recombination remains elusive. Here we demonstrate an interface‐engineering strategy that enables magnetic control of interlayer excitons by inserting a monolayer ferromagnet, CrSe 2 , as an atomic‐scale spin‐valve spacer within a twisted WSe 2 homobilayer. At low temperature, the twisted WSe 2 bilayer supports highly efficient conversion from intralayer to interlayer excitons, providing a sensitive platform to probe interlayer charge transfer. Introducing CrSe 2 suppresses interlayer coupling and produces pronounced thermomagnetic signatures near the Curie temperature (∼65 K), evidencing strong coupling between magnetic fluctuations and exciton dynamics. Under external magnetic fields up to 9 T, the interlayer‐exciton emission is reversibly modulated while intralayer emission is enhanced, consistent with spin‐selective tunnelling that regulates interlayer charge transfer. First‐principles calculations support CrSe 2 ‐mediated spin filtering and reveal stacking‐angle‐dependent charge transfer. These findings establish magnetic spin filtering as an effective strategy for manipulating excitonic states, opening pathways toward spin–exciton hybrid architectures and quantum optoelectronic devices at the atomic scale.

Altermagnetism, characterized by compensated antiparallel spin order accompanied by finite spin splitting, bridges the properties of ferromagnets and antiferromagnets and holds promise for next-generation spintronic applications. Theoretical studies suggest that twisting van der Waals layers can induce altermagnetic states by tuning interlayer symmetry, thereby expanding the family of magnetic quantum materials. However, direct experimental observation of altermagnetism in these systems has not been achieved. Here we demonstrate altermagnetism in orthogonally twisted CrPS4/CrPS4 homostructures using magneto-optical spectroscopy. This structure exhibits a ferromagnetic-like magnetic-field dependence of the degree of circular polarization. Furthermore, a pronounced Zeeman splitting—absent in either ferromagnetic or antiferromagnetic CrPS4—emerges in the twisted configuration, indicating a distinct magnetic ground state. First-principles calculations reveal large spin-split bands in an antiferromagnetic configuration, confirming the realization of altermagnetism in twisted CrPS4. Polarized Raman spectroscopy further identifies interlayer-coupling-induced phonon-mode splitting unique to the altermagnetic state. These findings provide experimental evidence of altermagnetism in a twisted van der Waals material. Altermagnetic states hold promise for spintronic applications but are yet to be observed in twisted van der Waals materials. Now an orthogonally twisted CrPS4 homostructure is shown to exhibit signatures of altermagnetism.

Parity symmetry enforces radiative degeneracy of parity-conjugated emitters in free space. We selectively lift this degeneracy in an achiral dielectric cavity via coupling-induced global parity breaking: the cavity and individual dipoles each preserve parity, while their fixed relative orientation breaks global parity, enabling differential decay. This mechanism exhibits a structure-function trend in marked contrast to the Rosenfeld rule: orthogonal electric-magnetic dipoles yield radiative asymmetry approaching the theoretical limit of 2, whereas parallel ones show negligible differentiation. A semi-analytical model, validated across multiple modes, confirms generality. These findings establish a new paradigm for symmetry engineering without intrinsic chirality.