2D magnetic materials offer a versatile platform for exploring emergent phenomena in condensed matter physics and spintronics. However, their limited environmental stability and relatively low magnetic ordering temperatures hinder both fundamental research and potential applications. Here, the synthesis of ultrastable 2D Fe3O4 nanosheets with a high Curie temperature (T-C) via a chemical vapor deposition (CVD) method employing an intermediate-state reduction strategy is reported. Comprehensive electrical and magnetic transport measurements reveal a pronounced metal-semiconductor-insulator transition (Verwey transition), accompanied by anomalous anisotropic magnetoresistance (AMR) exhibiting periodic evolution behaviors below Verwey transition temperature (T-V). Temperature-dependent Raman spectroscopy combined with first-principles calculations demonstrates that the Verwey transition originates from charge ordering and the formation of trimerons. The anomalous AMR is attributed to the competition between intrinsic uniaxial anisotropy and trimeron-mediated magnetic anisotropy. These findings advance the fundamental understanding of the Verwey transition, provide guidance for the scalable fabrication of 2D Fe3O4 nanosheets, and may facilitate future applications in spintronics.

The enhancement of plasmon-induced hot carrier injection efficiency in metal/semiconductor heterostructures is essential for boosting their photoelectronic performance. Nevertheless, the considerable lattice mismatch between the components hinders the development of clearly defined interfacial atomic structures, complicating the understanding of the interfacial structure's impact on hot carrier dynamics. Here, we demonstrate a ligand-assisted chemical transformation strategy to produce high-yield (>90%) epitaxial Ag/ZnS heterostructures from matchstick-like Ag2S/ZnS templates. It is found that the presence of a ligand promotes preferential nucleation of Ag nuclei at the interface, leading to well-defined interfacial structures. Comparative studies reveal that epitaxial interfaces in Ag/ZnS heterostructures significantly improve plasmon-induced hot electron transfer from Ag to ZnS under 520 nm excitation, achieving a quantum yield of 38.12%, nearly double that of nonepitaxial counterparts (21.11%), as quantified by near-infrared transient absorption pump-probe spectroscopy. Additionally, single-particle photothermal microscopy measurements demonstrate that the photothermal signals of epitaxial Ag/ZnS heterostructures display a uniform distribution with a decreased intensity compared to those of their counterparts, further correlating plasmonic heating characteristics of the heterostructures with their interfacial structure. This work establishes the importance of interfacial engineering in optimizing plasmon-induced hot carrier dynamics, offering insights into the design of high-performance optoelectronic devices utilizing plasmonic metal/semiconductor heterostructures.

Compact magneto-optical dichroism devices facilitate active and dynamic manipulation of photons at the chip scale, making them a key focus in the development of integrated photonic and optoelectronic systems. However, the performance of existing optical anisotropy materials is often constrained by their narrow operational bandwidth and temperature and insufficient magnetically induced tunability. Herein, we demonstrate robust and reconfigurable magneto-optical dichroism spanning the visible to near-infrared spectrum using a quasi-1D exciton-polariton cavity platform constructed from van der Waals CrSBr crystals. The platform demonstrates strong and multiparameter-tunable in-plane linear dichroism, responsive to magnetic field, temperature, and crystal thickness variations. The anisotropy in exciton-photon coupling is the origin of the superior and tunable in-plane anisotropy, which is enhanced by the optical cavity. We further demonstrate the effective modulation of the left- and right-circularly polarized components in anisotropy-induced optical spin-orbit coupling in CrSBr microcavities. These results offer valuable insights for the development of compact isolators, modulators, and polarizers for photonic, quantum, and optoelectronic applications.

Abstract Accurate optical gain measurement at the microscale has long been plagued by photorefractive effects that distort optical spectroscopy signals under high excitation conditions. Here, we develop a phase-sensitive microscopic transient white-light interferometry that disentangles gain dynamics from transient refractive index changes, enabling direct access to intrinsic gain in photorefractive materials. Applying this method to CsPbBr3 single-crystal microplatelets, we reveal that conventional measurements underestimate gain by up to 20%. The corrected gain exhibits a duration of 500 ps and a bandwidth of ∼30 nm. We further uncover that the optical confinement factor governs a nonmonotonic thickness dependence of gain, peaking at ∼140 nm. Exploiting this optimal cavity length in a DBR structure yields a lasing threshold of 0.07 μJ·cm–2. This work presents a general method for measuring gain in photorefractive micronano materials and offers design guidelines for high-performance microlasers and integrated photonic circuits.

Organic-inorganic hybrid perovskites (OIHPs) offer a promising alternative, combining strong spin-orbit coupling, high carrier mobility, and tunable optoelectronic properties. However, their potential for spintronic applications has been constrained by rapid spin relaxation, often attributed solely to the inorganic sublattice. Here, we demonstrate room-temperature spin transport in hybrid perovskites enabled by isotope engineering. Substituting hydrogen with deuterium in methylammonium lead iodide effectively suppresses hyperfine interactions (HFI), leading to a 2.6-fold increase in spin lifetime. As a result, CD₃ND₃PbI₃ exhibits a magnetocurrent (MC) ratio of 17.5% at room temperature, whereas conventional CH₃NH₃PbI₃ spin-valve devices show negligible MC response. A spin photovoltaic effect is also observed under ambient conditions, revealing a coupling between optical excitation and spin-polarized transport, and pointing toward new opportunities for light-addressable spintronic functionality. These findings not only revise the fundamental understanding of spin relaxation in hybrid materials, but also establish isotope engineering as a powerful strategy to access room-temperature spin functionality.

Exciton-polaritons provide a great platform for developing ultrafast all-optical logic gates for quantum and optical chips. However, progress toward practical polariton logic remains limited due to incomplete logical functionality on a single device. Herein, we present a single-device perovskite polariton platform enabling reconfigurable, ultrafast logic gates with functional completeness. The device consists of an optically trapped perovskite microwire, generating well-controlled non-equilibrium polariton condensation states for multiple logic operation channels. By tailoring the power of signal and gate beams, the same device is programmed to execute three basic Boolean functions (AND,OR,and NOT) and a high-order XOR function with a high on/off ratio of 21 dB, and a fast response time 6.7 ps. The reconfigurability arises from the selective activation of different nonlinear responses of polariton condensates, including amplification, seeding state transitions, and nonlinear interaction. These results provide valuable insights for advancing exciton-polariton logic gates.

Efficient tuning of structural distortion is an attractive approach for regulating self-trapped excitons emission properties of two-dimensional halide perovskites. Nevertheless, it remains elusive as to how the structural distortion is related with such emission. Here, we elucidate the relationship between structural distortion and the emission behavior of self-trapped excitons in two-dimensional lead bromide perovskites (R-NH3)2PbBr4 (where R is the cyclic carbon group). We reveal that rather than the octahedral tilting distortion, the lone pair activity-induced Jahn-Teller distortion plays a significant role in self-trapped excitons emission. Consequently, with growing ring size of cyclic organic cation, the increased Jahn-Teller distortion results in a larger relative self-trapped excitons emission due to the enhanced short-range Holstein electron-phonon coupling strength. Our work clarifies the controversy of the structural distortion correlation on self-trapped excitons emission and provides valuable insights for structural engineering in white-light emitting applications of two-dimensional perovskites.

ABSTRACT Chiral hybrid organic–inorganic metal halides (HOIMHs) hold great promise for nonlinear optical (NLO) applications. However, their practical applications are severely hindered by the poor environmental stability and photostability. Herein, guided by the hard and soft acids and bases (HSAB) theory, we quantitatively calculated and compared the chemical hardness of all elements in the periodic table based on density functional theory, and found osmium (Os) exhibits the highest chemical hardness among Group VIII transition metals. Thus, we synthesized the chiral osmium‐based HOIMHs, ( R / S ‐3BrMBA) 2 OsCl 6 ( R / S ‐Os ), and systematically investigated their NLO properties and stability. As expected, the obtained chiral osmium halides remain stable after two months of exposure to air, and the second‐harmonic generation (SHG) intensity remains almost unchanged after the same period, confirming their outstanding long‐term stability. The efficient SHG responses with effective second‐order nonlinear susceptibility ( χ eff ) of 6.4 pm/V and strong SHG circular dichroism (SHG‐CD) with anisotropy factor (| g SHG‐CD |) of 0.33 are also observed. Our work provides valuable HSAB‐guided screening strategy for predicting and designing the highly stable NLO materials.

In this study, chiral carbon nanorings D3-(P)-NR5 and D3-(M)-NR5 with outstanding chiral linear and nonlinear optical properties were synthesized. They exhibit excellent circularly polarized luminescence (CPL) with a high CPL brightness of 1008 M-1 cm-1 and a significant second-harmonic generation circular dichroism response with a high anisotropy factor of up to 0.59.

Control over excited-state deactivation in multichromophoric assemblies is critical for advancing functional optoelectronic materials. While shape-persistent macrocycles provide a robust platform to suppress nonradiative relaxation via structural rigidity, their cyclic architecture often weakens electronic coupling, creating a trade-off between conformational constraint and deactivation pathway control. To address this challenge, we present two shape-persistent ortho-alkynyl-linked PDI macrocycles (Dimer and Trimer) that exhibit solvent-polarity-controlled switching between competing deactivation manifolds. By combining transient absorption spectroscopy with chemical calculations, we discover that in nonpolar toluene, ortho-alkynyl substitution activates a highly efficient, heavy-atom-free intersystem crossing pathway, with triplet yields increasing from the Dimer (∼65%) to the Trimer (∼85%). This enhancement is attributed to a higher density of near-resonant triplet states that compensates for decreased excitonic coupling. Conversely, increasing solvent polarity triggers ultrafast symmetry-breaking charge separation (SB-CS) on a picosecond time scale, which effectively outcompetes the triplet formation. These insights highlight the utility of rigid and weakly coupled molecular constructs in controlling triplet generation and SB-CS for potential applications in optoelectronic devices.

Semiconductor nanowires (NWs), which use semiconductor materials as optical gain media and simultaneously act as waveguides and optical cavities, can serve as on-chip amplifiers, lasers, modulators, and waveguides. They are widely regarded as key building blocks for next-generation photonic integrated circuits. Realizing these multifunctional applications requires long NWs with high optical gain and superior waveguide properties. In this study, we synthesized single-crystalline CsPbBr3 NWs with subwavelength widths and lengths up to 300 μm via chemical vapor deposition. The resulting NW exhibits high-quality lasing performance, with a quality factor (Q factor) of 5538, along with outstanding waveguide properties, achieving a low loss coefficient of 0.88 dB mm-1. Based on these advantages, we developed an integrated laser-waveguide device that performs all-optical OR/AND logic and enables cascaded signal transmission under dual-pulse excitation. Our work highlights the potential of perovskite NWs for integrated nanophotonics.

The controlled doping of organic semiconductors is a promising strategy for optimizing the charge transport and optoelectronic performance in organic devices. Herein, we report a Br & oslash;nsted acid doping method using the tris(pentafluorophenyl)borane-water complex [B(C6F5)(3)-H2O] to modulate the molecular ordering and charge dynamics of PBTTT-C14/PCBM heterojunctions. The air-exposed B(C6F5)(3) (BCF) forms a stable Br & oslash;nsted acid complex capable of protonating PBTTT-C14, leading to enhanced charge delocalization and reduced trap density. The optimized 2 wt % BCF-H2O-doped PBTTT-C14/PCBM film exhibited a carrier mobility of 6.89 & times; 10(-2) cm2V(-1)s(-1), a responsivity of 343.57 A/W, and a photocurrent-to-dark-current ratio of 2.3 & times; 10(5), representing nearly a 3-fold improvement over the pristine film. Spectroscopic analysis (B-11 NMR, EPR, and UV-vis-NIR) confirms successful doping, while transient absorption and GIXRD measurements reveal a prolonged exciton lifetime, enhanced crystallinity, and improved molecular orientation. This work provides a straightforward approach to high-performance phototransistors via Br & oslash;nsted acid doping of conjugated polymers.

In semiconductors where three-phonon decay channels are suppressed, a mechanism termed "hot-phonon delocalization" induced by higher-order anharmonic decays emerges as the dominant process governing carrier thermalization. By combining ab initio solutions of the time-dependent coupled electron-phonon Boltzmann transport equations with femtosecond stimulated Raman spectroscopy, this study demonstrates that four-phonon couplings can substantially reshape the non-equilibrium carrier dynamics in semiconductors with significant phonon gaps, such as BAs and BSb. The results show that momentum-redistribution channels, specifically o+o→o+o and o+a→o+a, effectively delocalize hot phonons that initially accumulate in long-wavelength states by spreading them across the Brillouin zone. This behavior is fundamentally different from the conventional picture, where hot-phonon relaxation is assumed to be governed primarily by emission processes. This mechanism suppresses hot-phonon accumulation and enhances the efficiency of three-phonon Ridley- and Vallée-Bogani-type decays, mitigating the phonon bottleneck effect and ultimately improving Joule heating efficiency. In BAs, four-phonon coupling increases the energy dissipation rate of optical phonons nearly 70-fold, reducing phonon reabsorption and enabling high-energy electrons and holes to continuously emit optical phonons, as supported by our proposed phenomenological model. Consequently, the onset of phonon reabsorption heating is delayed from 6.0 to 12.9 ps. These findings provide a comprehensive understanding of carrier thermalization, revealing that hot-phonon delocalization governs energy-exchange pathways in wide-phonon-gap semiconductors on the picosecond timescale.

Second-harmonic generation in centrosymmetric magnetic materials is typically restricted below the Néel temperature; above this threshold, symmetry breaking requires the application of external fields. Here, we report the first observation of robust second-harmonic generation at ambient temperature in a centrosymmetric magnetic material without the application of external stimuli. By integrating chromium sulfide bromide (with a Néel temperature of 136 K) with aligned silver nanowires, we simultaneously induce uniaxial strain and plasmonic near-field enhancement, driving a persistent structural transition from orthorhombic to monoclinic symmetry. This dual activation mechanism enables the coexistence of anisotropic strain-induced and magnetization-assisted second-harmonic generation, yielding a strong nonlinear optical response under ambient conditions. Furthermore, we demonstrate a functional magneto-optical device operating under ambient, establishing a broadly applicable framework for accessing nonlinear optical phenomena in centrosymmetric quantum materials at room temperature.

Single-crystal wafers of p-type two-dimensional (2D) semiconductors are highly desired for next-generation electronics. However, p-type 2D semiconductors remain scarce, and achieving wafer-scale monolayer single crystals of such materials is even more challenging. Here we report the wafer-scale growth of p-type semiconducting monolayer MoSi2N4 single crystals on Cu (111) foils with prestored Mo and Si atoms. The <110> steps on Cu (111) guide the nucleation and unidirectional orientation of monolayer MoSi2N4 domains, enabling their seamless stitching into a continuous single-crystal film. The resulting MoSi2N4 exhibits exceptional quality, with an intrinsic mobility of 154 cm2 V-1 s-1. Field-effect transistor arrays fabricated from this material deliver excellent electrical performance, including an on/off ratio of ~3.8 ± 1.4 × 106 and an on-state current density up to ~17.96 μA μm-1 (1 μm channel length), along with superior stability compared with monolayer WSe2-based counterparts. Furthermore, this versatile growth strategy also enables the fabrication of wafer-scale monolayer WSi2N4 single crystals. This work establishes a promising p-type 2D semiconductor platform for future integrated circuits.

Bound states in the continuum (BICs) in microcavity polaritons offer a compelling platform for the interplay of photonic topology and excitonic nonlinear features, yet existing studies are mostly restricted to fundamental resonance modes that restrict access to rich multimode interactions. Here, we demonstrate the realization of a robust higher order mode of BIC in FAPbBr3 perovskite photonic crystals, with a meticulous design of energy detuning for photon and exciton resonance. We show numerically that the higher order mode of BIC exhibits excellent resilience against index asymmetry and fabrication perturbations, robustly sustaining high quality factors. On the basis of this platform, we achieve strong coupling between a second order mode of BIC and perovskite excitons and realize polariton lasing operated at room temperature. The polariton lasing exhibits a coherent far-field polarization vortex carrying a topological charge of -1. This work establishes a promising platform for exploring nonlinear polaritonic phenomena and topological light emission.

ABSTRACT 2D magnetic materials offer a versatile platform for exploring emergent phenomena in condensed matter physics and spintronics. However, their limited environmental stability and relatively low magnetic ordering temperatures hinder both fundamental research and potential applications. Here, the synthesis of ultrastable 2D Fe 3 O 4 nanosheets with a high Curie temperature (T C ) via a chemical vapor deposition (CVD) method employing an intermediate‐state reduction strategy is reported. Comprehensive electrical and magnetic transport measurements reveal a pronounced metal‐semiconductor‐insulator transition (Verwey transition), accompanied by anomalous anisotropic magnetoresistance (AMR) exhibiting periodic evolution behaviors below Verwey transition temperature (T V ). Temperature‐dependent Raman spectroscopy combined with first‐principles calculations demonstrates that the Verwey transition originates from charge ordering and the formation of trimerons. The anomalous AMR is attributed to the competition between intrinsic uniaxial anisotropy and trimeron‐mediated magnetic anisotropy. These findings advance the fundamental understanding of the Verwey transition, provide guidance for the scalable fabrication of 2D Fe 3 O 4 nanosheets, and may facilitate future applications in spintronics.

In metal-coordinated covalent organic framework (COF)-based photocatalytic systems, the coordination environment of metal sites critically determines the electronic structures and charge transfer behavior of the metal centers, thereby affecting the catalytic performance. In this work, a vinylene-linked COF containing phenylpyridine units (TMT-ppy-COF) was constructed to generate cyclometalated Pt (C^N–Pt) sites, forming a mixed Pt–N and Pt–C coordination mode. Unlike conventional metal–N coordination, the cyclometalation process proceeds through initial pyridyl coordination followed by ortho-C–H activation of the adjacent phenyl ring, yielding a five-membered C^N-chelated metallacycle at the Pt site. The as-prepared Pt-TMT-ppy-COF maintains good crystallinity and microporosity. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and Pt L3-edge X-ray absorption spectroscopy reveal atomically dispersed Pt species without detectable Pt–Pt bonding in the material. X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy, and photoelectrochemical measurements indicate enhanced charge separation, prolonged excited-state lifetimes, and lower charge transfer resistance for Pt-TMT-ppy-COF compared to pristine TMT-ppy-COF. Under visible-light irradiation (λ ≥ 420 nm), Pt-TMT-ppy-COF with an optimal Pt loading of 6.42 wt% exhibits a hydrogen evolution rate of 10,574.1 μmol g−1 h−1 and good recyclability. Density functional theory (DFT) calculations further show that cyclometalation modulates the frontier orbitals around the Pt coordination environment, promotes electron accumulation at the Pt site, and optimizes H* adsorption. This work identifies cyclometalation as an effective strategy for enhancing photocatalytic hydrogen evolution in COFs.

Single-atom catalysts (SACs) with atomically dispersed active centers exhibit high catalytic efficiency. However, simultaneously achieving high metal loading and scalable synthesis of SACs remains a major challenge, greatly limiting their practical deployment. Herein, we design a chemically robust covalent organic framework (COF) featuring an ordered porous structure and the precisely engineered coordination environment to immobilize single metal atoms at a relatively high loading. The vinylene-linked COF (PZBpy-COF) was synthesized through a solvent-free melt polymerization of tetramethylpyrazine and bipyridine monomers, followed by coordination of nickel (Ni) ions to afford Ni-PZBpy-COF with a high metal loading of 6.4 wt%. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy imaging confirms the uniform atomic dispersion of Ni sites throughout the COF matrix. Ni-PZBpy-COF shows an outstanding carbon dioxide (CO2) photoreduction activity under visible-light irradiation, affording a carbon monoxide (CO) evolution rate of 5270 μmol g-1 h-1 with 90% selectivity for CO over hydrogen (H2) evolution. Notably, the solvent-free strategy enables gram-scale preparation of PZBpy-COF while preserving crystallinity, porosity, uniform single-atom dispersion, and photocatalytic performance, addressing the scalability gap of COF-based photocatalysts predominantly synthesized at the milligram scale. The integration of COF structural tunability and synthetic scalability with the atomic precision of single-atom catalysts offers a viable route toward practical applications.