Superconducting radiofrequency (SRF) cavities are essential for high-energy particle accelerators rendering ultralow power dissipation and a high acceleration gradient. We demonstrate a superior performance in niobium-based 1.3 GHz cavities via medium-temperature (Mid-T) baking with remarkable values up to 5.5 × 1010 for the quality factor (Q0) at 16 and 32.7 MV/m for the maximum acceleration gradient (Eacc). Through correlative in situ spectroscopy, mass spectrometry, and electron and tunneling microscopy, we establish that nanoscale spatial distributions of impurities (O, C, H) directly evidenced at the metal-oxide interface govern performance enhancement. In niobium, annealing at 300 °C drives uniform oxygen doping (10-100 nm depth) via diffusion from the native oxide, while an optimized Mid-T protocol in delivering high Eacc values suppresses interfacial NbO segregation through competitive C-O interactions. For the optimized protocol, post-treatment characterization reveals up to an 8.8% increased superconducting gap and 29.7% reduced quasiparticle broadening, corroborating strain-mediated defect-impurity interactions at proximity layers. These results provide a Mid-T baking recipe to simultaneously enhance Q0 and maximum Eacc in SRF cavities via competitive impurity interactions at the metal-oxide interface.

The superconducting diode effect (SDE) is a fascinating nonreciprocal phenomenon where the critical current is different for opposite current directions. It is widely believed that realizing SDE requires breaking both inversion symmetry and time-reversal symmetry (TRS), which are usually achieved via heterostructure engineering and applying external magnetic fields. Here, we report a pressure-induced magnetic-field-free SDE in NbSe_{2} flakes without any heterostructures. We show that pressure alone breaks the inversion symmetry, as confirmed by the second harmonic generation. Crucially, upon applying an out-of-plane magnetic field (B), the SDE exhibits even-in-B behavior, implying the absence of explicit TRS breaking. This finding challenges the prevailing theoretical paradigm and demonstrates that a magnetic-field-free SDE can emerge without explicitly breaking TRS. Thereby, our Letter establishes pressure engineering as a powerful tool for inducing nonreciprocal superconductivity and designing versatile, magnetic-field-free superconducting devices.

Two-dimensional conductive metal-organic frameworks (2D c-MOFs) have emerged as highly promising advanced functional materials with enormous application potential, among which Ni3(HITP)2, an emerging 2D c-MOF material, has garnered widespread research attention due to its unique structural and electronic properties. However, the precise modulation of the gas-sensing performance of Ni3(HITP)2 remains a critical challenge in the 2D c-MOFs research community. To address this challenge, we propose a rational dual-functionalization modulation strategy via the synergistic integration of metal oxide quantum dots and noble metal nanoparticles, with the aim of providing new insights for the performance modulation of 2D c-MOFs. In detail, 2D Ni3(HITP)2 nanosheets were initially fabricated through a solvothermal method, subsequently functionalized with SnO2 quantum dots (QDs) to form robust heterostructures, and finally decorated with Au nanoparticles for further modification. This dual-functionalization strategy effectively regulated and significantly enhanced the NO2-sensing properties of Ni3(HITP)2, with core performance metrics including: a high response of 30.49% toward 100 ppm, fast response/recovery dynamics of 24 s/55 s, an ultralow detection limit down to 90 ppb, along with excellent repeatability, superior long-term stability, and excellent humidity resistance. First-principles density functional theory (DFT) calculations were performed to elucidate the intrinsic modulation mechanism, confirming the crucial roles of Au nanoparticles and SnO2 QDs. This work successfully achieves effective regulation of Ni3(HITP)2 and provides a generalizable and feasible strategy for the performance optimization of 2D c-MOF materials.

Achieving controllable orientation growth of MoS2 on sapphire substrates is critically important. However, existing approaches typically rely on prolonged high-temperature substrate preannealing, which involves complex processes and high costs. In this work, we propose a facile strategy based on liquid-precursor chemical vapor deposition, achieving substrate engineering and oriented growth in one step by introducing the KCl additive. Our results show that Cl- can induce the formation of nanoscale steps on the sapphire surface during growth. These steps act as preferential nucleation sites, effectively guiding MoS2 domains to adopt a dominant orientation. Field-effect transistors fabricated from the resulting MoS2 exhibit stable n-type behavior and high current on/off ratios. This work presents a low-cost orientation-control strategy based on Cl--induced step engineering, providing a practical pathway toward growth of high-quality two-dimensional transition metal dichalcogenides.

The moiré superlattice in twisted transition metal dichalcogenides (TMDCs) offers a versatile platform for exploring electronic properties and correlated quantum phenomena. However, conventional fabrication methods using transfer and stacking techniques suffer from interfacial contamination and limited scalability. Here, we introduce an in situ focused electron beam irradiation approach to dynamically manipulate and characterize the moiré superlattice in bilayer 2H-WS2 in TEM. We achieve real-time moiré pattern control, enabling precise twist angle adjustments (6-10°). Prolonged irradiation induces displacement of tungsten (W) and sulfur (S) atoms from the moiré superlattice, which migrate to heal vacancies in adjacent monolayers, ultimately collapsing the superlattice into a WS2 monolayer and revealing an unexpected atomic-scale self-repair mechanism. This technique advances the study of twistronics in 2D quantum materials by providing a pathway for atomically precise engineering of moiré-driven electronic states while highlighting the potential of electron beam lithography (EBL) for the controllable fabrication of moiré devices.

Magnetic/superconducting heterostructures represent a frontier in condensed matter physics, offering pathways to realize unconventional pairing mechanisms such as topological superconductivity, spin-triplet pairing, and Majorana zero modes for fault-tolerant quantum computing. In this work, we integrate the magnetic van der Waals material MnBi2Te4 (MBT) with a superconducting NbN thin film, achieving ultralow-disorder interfaces through Ti buffer layer engineering. Temperature- and field-dependent critical currents, extracted from differential resistance spectra, reveal robust coupling between the MnBi2Te4 and the superconducting order of NbN, enabling proximity-induced superconductivity within MnBi2Te4. Notably, the proximity-induced critical currents remain invariant under in-plane field rotation, in contrast to the anisotropic response observed in pristine NbN. Moreover, the hysteretic behavior observed in the interfacial magnetoresistance curves confirms the proximity-induced spin polarization at the MBT interface, which is consistent with Andreev reflection results. These findings demonstrate a platform for fabricating high-quality heterointerfaces and enable targeted exploration of exotic quantum states.

Spinel oxides are important photothermal conversion material. ZnCo2O4, Co3O4, and CoAl2O4 were used as model spinel systems to investigate the influence of cation geometric configuration on photothermal conversion. In these systems, all of the octahedral sites (Oh) are occupied by Co3+ while all of the tetrahedral sites (Td) are occupied by Co2+. Experimental results indicate that Co3+-Oh (ZnCo2O4) exhibits a higher photothermal conversion efficiency (85.7%) than Co2+-Td (74.0%) under a light intensity of 94 W/m2. The superior performance of Co3+-Oh over Co2+-Td is attributed to the reduced bandgap, which enhances nonradiative transitions and electron-phonon coupling, thereby improving photothermal conversion efficiency. Furthermore, subsequent Ni doping into the Co3O4 framework promotes the migration of Co ions into octahedral sites, further improving the photothermal conversion efficiency to 86.5%, which surpasses the commercial material Pyromark 2500. This work elucidates the structure-property relationship of spinel-based photothermal materials and identifies the optimal geometric configuration.

Distributed quantum sensing has important applications in quantum-enhanced estimation of global parameters, which is the weighted sum of each sensor. Towards applications, it is essential to estimate more global parameters simultaneously. Here, we propose an improved quantum-enhanced distributed multi-parameter sensing of more than two global parameters simultaneously via Gaussian multipartite entanglement. We show that two global parameters, containing the real and imaginary parts of the complex amplitudes of multiple radio-frequency fields, can be estimated based on an Einstein-Podolsky-Rosen entangled state. Compared to the distributed quantum sensing with squeezed light in the same sensing network, the sensors are extended from M to 2M in the improved scheme with multipartite entanglement. This work provides a practical approach for advancing high-precision multi-parameter quantum sensing technologies.

The superconducting diode effect (SDE), a nonreciprocal phenomenon where the critical supercurrent differs depending on the direction of current flow, is a promising foundation for superconducting logic and memory. Realizing its full potential requires a diode that operates without an applied magnetic field, which generally requires the breaking of both time-reversal and inversion symmetries in the superconducting system. Zero-field SDEs are often observed in heterostructures but remain rare in single materials. Here, we report the observation of a robust, field-free SDE in thin flakes of FeTe0.55Se0.45. A sensitive probe of nonreciprocal transport is the emergence of a pronounced second harmonic response near the superconducting transition under zero applied field, with an amplitude comparable to the standard first harmonic signal. The SDE persists at zero field and maintains its polarity under both large positive and negative magnetic fields, exhibiting an even-in-field symmetry that distinguishes it from mechanisms based on finite-momentum pairing or magnetochiral anisotropy. We systematically rule out alternative origins, including device geometry, thermal gradients, chiral domains, and extrinsic magnetic order. Instead, our analysis indicates that local strain/polarization-induced symmetry breaking is a primary factor in generating and enhancing the effect. These results identify iron-based high-temperature superconducting platforms as highly promising candidates for the field-free superconducting diode effect, benefiting from their coexistence of strong intrinsic disorder and superconductivity in a structurally simple form.

Superconducting radiofrequency (SRF) cavities are essential for high-energy particle accelerators rendering ultralow power dissipation and a high acceleration gradient. We demonstrate a superior performance in niobium-based 1.3 GHz cavities via medium-temperature (Mid-T) baking with remarkable values up to 5.5 x 1010 for the quality factor (Q 0) at 16 and 32.7 MV/m for the maximum acceleration gradient (E acc). Through correlative in situ spectroscopy, mass spectrometry, and electron and tunneling microscopy, we establish that nanoscale spatial distributions of impurities (O, C, H) directly evidenced at the metal-oxide interface govern performance enhancement. In niobium, annealing at 300 degrees C drives uniform oxygen doping (10-100 nm depth) via diffusion from the native oxide, while an optimized Mid-T protocol in delivering high E acc values suppresses interfacial NbO segregation through competitive C-O interactions. For the optimized protocol, post-treatment characterization reveals up to an 8.8% increased superconducting gap and 29.7% reduced quasiparticle broadening, corroborating strain-mediated defect-impurity interactions at proximity layers. These results provide a Mid-T baking recipe to simultaneously enhance Q 0 and maximum E acc in SRF cavities via competitive impurity interactions at the metal-oxide interface.

Nickelate superconductors constitute the third unconventional high-temperature superconducting family after copper-based superconductors and iron-based superconductors, and have been a research hotspot in the fields of superconducting materials and physics in recent years. Among them, ambient-pressure nickelate superconducting thin films have attracted significant attention due to their convenience in physical research and potential future applications. This review summarizes recent advances in the study of nickelate superconducting thin films under ambient pressure, with a focus on film synthesis, property modulation, and mechanistic investigation of infinite-layer and bilayer Ruddlesden-Popper (RP) phase nickelates. We systematically analyze the characteristics and applicability of key fabrication techniques, including pulsed laser deposition (PLD), oxide molecular beam epitaxy (OMBE), and gigantic-oxidative atomic-layer-by-layer epitaxy (GOALL-Epitaxy). The research results demonstrate that through multi-element doping and strain engineering, the superconducting transition temperature of infinite-layer nickelate film has been enhanced to nearly 40 K. Moreover, bilayer RP nickelate thin films have achieved superconducting transitions with onset temperatures exceeding 60 K at ambient pressure, exhibiting zero resistance, complete diamagnetism, and unconventional superconducting phase diagrams. We provide a outlook regarding the further development of nickelate thin film fabrication technologies, the discovery of novel material systems, and the elucidation of their microscopic pairing mechanisms.

The entangled charge and spin dynamics in strongly electron correlated system has been a fruitful playground for exploring new physical phenomena. Here with resonant inelastic X-ray scattering we studied the spin dynamics of SrIrO_3, a half-filled paramagnetic semimetal hosting highly itinerant Dirac Fermions due to its topological band structure. Our results show that its magnetic excitations share much similarity to the ordered compounds upon Sn substitution in exchange strength and AFM instability, while the system maintains spin non-ordered. Further, the non-ordered pristine SrIrO_3 hosts even longer lifetime magnetic excitations near the AFM zone center comparing to the Sn substituted ordered compounds, contrary to general expectation. These observations indicate an interesting connection between band topology and electron correlation in SrIrO_3.

Abstract Layered topological insulators such as Bi 2 Se 3 exhibit rich phonon dynamics, which are crucial for understanding their thermal transport mechanisms and electronic properties. In this work, we investigate the multiscale nonequilibrium lattice dynamics in Bi 2 Se 3 thin films using ultrafast transmission electron microscopy (UTEM). By exploiting the complementarity between real-space ultrafast electron microscopy (UEM) and ultrafast electron diffraction (UED), we show that the characteristic frequencies of the lattice dynamics are consistent in real and reciprocal space. This cross-validation supports the interpretation that the transient anti-phase oscillation of Friedel diffraction pairs originates from reciprocal-space geometric evolution induced by the breathing mode: under large-angle tilting, reciprocal rods with nonzero out-ofplane Miller indices undergo periodic stretching and displacement along the c * axis, thereby asymmetrically changing their intersections with the Ewald sphere. This process corresponds directly to the coherent motion of lattice bend contours observed in real space. The study further reveals that phonon propagation exhibits pronounced scale dependence. On the picosecond timescale, the dynamics are dominated by a longitudinal standing-wave breathing mode confined by the film thickness, with the oscillation frequency following an inverse dependence on film thickness. Under the [001] zone-axis condition, defect-mediated in-plane traveling waves propagating at the speed of sound are observed. Furthermore, on the nanosecond timescale, the suspended thin film exhibits mechanical resonance with a high quality factor, accompanied by a rich spectrum of higher-order harmonics. These findings provide direct visual evidence for the multilevel dynamical responses of coherent phonons under the same pump excitation, manifesting at different timescales and boundary conditions from the gigahertz (GHz) to megahertz (MHz) regime, highlighting the potential of Bi 2 Se 3 for high-frequency nanomechanical applications.

Abstract MoS2 nanoscrolls can be intrinsically chiral quasi-1D materials, yet the influence of chirality on their electrical characteristics remains unresolved, since chirality metrology and device measurement have rarely been achieved on the same individual scrolls. In this work, we integrate polarization-resolved second-harmonic generation (SHG) with transistor characterization on MoS2 nanoscroll devices to address this long-standing question. We develop a unified SHG fitting model to extract an effective chiral angle (φ) for each scroll and establish a systematic correlation between transfer characteristics and structural parameters. The on-state current decreases with increasing |φ| and is further influenced by a strain-related parameter, whereas the off-state current correlates more closely with an SHG-derived winding/thickness indicator, consistent with electrostatic screening in multi-turn channels. These findings clarify the role of chirality and related geometric parameters in defining the transport properties of low-dimensional systems and provide useful insights for chirality-based nanoelectronics.

Transition metal phosphorus sulfides (MPS3), a family of two-dimensional magnetic materials with a van der Waals structure, exhibit promising applications in nonlinear optical devices. The emergence of carrier coherence in MPS3 is a fascinating topic in coherently controlling the nonlinear effect (or other novel phenomena). Herein, we systematically investigated the third-order nonlinear optical responses of MPS3 (M = Ni, Fe, Mn) flake suspensions based on spatial self-phase modulation (SSPM) effect. The effective monolayer third-order nonlinear susceptibilities (chi(3) monolayer) of NiPS3 and MnPS3 are obtained for the first time at multiple wavelengths. Our results show that NiPS3 has a higher chi(3) monolayer value (3.59 x 10-9 e.s.u. or 5.01 x 10-17m2V-2 at 405 nm excitation) than those of FePS3 and MnPS3. Furthermore, we laser-induced non-local hole coherence in MPS3 based on SSPM, where the origin of excited-state holes is analyzed from electronic structures. The relationships between hole mobility mu hole, effective mass m & lowast;h, and chi(3) monolayer for the three materials fulfill the previous investigation results. Because laser-induced hole coherence has rarely been reported, our investigation enriches the coherent regulation of two-dimensional magnetic MPS3 materials, enabling potential applications in all-optical devices. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Exploring advanced techniques capable of probing nanometric acoustic waves in nanostructures is critically important for the development of miniaturized acoustic devices.In this study,we probe the optically-excited acoustic waves in a single silicon nanowire(NW)using the time-resolved(tr-)high-order Laue-zone(HOLZ)lines under convergent-beam electron diffraction(CBED)conditions in an ultrafast transmission electron microscope(UTEM).We devise an experimental scheme to obtain tr-HOLZ lines under off-zone-axis CBED conditions.We also propose a geometric description of HOLZ line formation and use this alternative description to quantitatively evaluate the dynamics of optically-excited silicon NW.Using part of the deformation gradient tensor,our simulations of the dynamics of Si NW reproduce the experimental results.We further discuss the feasibility of a full retrieval of the deformation gradient tensor by using a set of HOLZ lines from three zone axes.Our findings illustrate a strategy for the quantitative access to dynamical acoustic waves optically excited in micro-and nano-structures using UTEM.

The superconducting diode effect (SDE) - the asymmetry of critical currents with respect to current direction - is a pivotal advancement in non-reciprocal superconductivity. While SDE has been realized in diverse systems, a fundamental challenge remains achieving field-free operation in iron-based superconductors with simple device geometries. Here, we report a non-volatile, field-free SDE in thin crystalline FeTe_0.55Se_0.45(FTS), showing asymmetric critical currents with a rectification coefficient of 1.9

Two-dimensional (2D) ferroelectrics with high Curie temperature (Tc) exhibit stable ferroelectricity at the nanoscale and possess significant applications in the miniaturization of ferroelectric devices. However, controllable growth of wafer-scale 2D ferroelectric films with desired thickness is still rarely reported. In this study, we develop a two-step vapour deposition method to grow wafer-scale 2D CuCrS2 ferroelectric films with a uniform thickness from 2 to 10 nm. These films possess a non-centrosymmetric structure with a 3R stacking sequence, exhibit ferroelectric polarizations, and the Tc of CuCrS2 is higher than room temperature. The constructed electronic devices exhibit the characteristics of ferroelectric memristor, which opens up applications for ferroelectric functional devices.