Accepted
, , Received Date: 2025-09-12
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, , Received Date: 2025-10-10
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With the rise and widespread applications of three-dimensional (3D) heterogeneous integration technology, inductive voltage regulators are becoming increasingly important for mobile terminals and high-computing-power devices, while also offering significant development opportunities for high-frequency soft magnetic films. According to the requirements of on-chip power inductors, we first review the advantages and limitations of three types of magnetic core films: permalloy, Co-based amorphous metal films, and FeCo-based nanogranular composite films, with a focus on the technical requirements and challenges of several μm-thick laminated magnetic core films. Secondly, almost all on-chip inductors are hard-axis excited, which means that the magnetic field of inductors should be parallel to the hard axis of the magnetic core. We thus compare the characteristics of two methods of preparing large-area films, i.e. applying an in-situ magnetic field and oblique sputtering, both of which can effectively induce in-plane uniaxially magnetic anisotropy (IPUMA). Their influences on the static and high-frequency soft magnetic properties are also compared. The influences of film patterning on the domain structures and high-frequency magnetic losses of magnetic cores, as well as corresponding countermeasures, are also briefly analyzed. Furthermore, the temperature stability of magnetic permeability and anisotropy of magnetic core films is discussed from the perspectives of process compatibility and long-term reliability. Although the Curie temperatures and crystallization temperatures of the three types of magnetic core films are relatively high, the upper limits of their actual process temperatures are affected by the thermal effects on the alignment of magnetic atomic pairs, microstructural defects, and grain size. Finally, the current bottlenecks in testing high-frequency and large-signal magnetic losses of magnetic core films are discussed, and potential technical approaches to achieving magnetic core films that meet the future demands of on-chip power inductors for higher saturation current and lower magnetic losses are outlined.
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Multi-Plane Light Conversion (MPLC) coherent beam combining (CBC) presents a promising approach for flexible optical field manipulation, overcoming the limitations of low energy utilization and poor beam quality in traditional CBC methods. However, its potential for generating diverse structured beams and the underlying design principles remain underexplored. In this work, theoretical model of MPLC-based CBC system was constructed to perform numerical investigation on the property and capability of MPLC optical field manipulation. Localized phase coding and vortex phase coding methods were proposed for mode mapping design to enhance the match between input and output modes. By employing multi-dimensional evaluation metrics including conversion efficiency (η), side-lobe suppression ratio (SSR), and phase matching degree (PMD), the performance of different coding strategies was systematically compared. The results manifested that while random coding yielded an average efficiency of 92% for five multi-focus beams, both localized and vortex coding significantly enhanced output quality, achieving a superior average efficiency of 97.1%. Based on the proposed encoding methods, MPLC successfully produced 5 Laguerre-Gaussian (LG) beams, 5 geometric shapes, and 5 letter patterns with remarkably high average efficiencies, reaching 97.4%, 99.2%, and 96.5%, respectively, accompanied by high SSR (>14 dB) and PMD (>96%). Furthermore, a strategy for arbitrary beam shaping by decomposing the target field into a linear combination of orthogonal modes was proposed and confirmed using a 21-mode MPLC. Simultaneously, its flexibility and the consequential requirement for strong amplitude modulation on the laser array were discussed. Finally, the relationship between the number of supported modes and the required number of phase plates was also analyzed, illustrating that maintaining high efficiency for a larger number of modes necessitates a significant increase in the number of phase plates. This study effectively generated a wide range of structured beams with minimal stray light and high energy utilization, demonstrating that MPLC-based CBC is a powerful and versatile technique for high-efficiency, high-quality optical field manipulation. Future work should focus on optimizing the design to reduce the requisite number of planes, paving the way for practical applications in high-power laser processing, optical communications, and quantum optics.
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Mid-infrared quantum light sources hold broad application prospects in fields such as gas sensing and infrared thermal imaging. However, currently used mid-infrared quantum entanglement light sources primarily rely on bulk periodically poled lithium niobate (PPLN) crystals, which suffer from limitations in both brightness and integration. This paper proposes a theoretical scheme based on lithium niobate thin films utilizing a 1556.9 nm pump to generate entangled photon pairs with a central wavelength of 3113.8 nm. Through optimized waveguide structure and periodic polarization design, Type-II phase matching and group velocity matching are achieved. This enables transverse electric (TE)-polarized pump input to downconvert to generate photon pairs with TE and transverse magnetic (TM) polarization. Furthermore, by combining a domain arrangement algorithm for customized design of the PPLN waveguide’s polarization direction, precise phase matching is achieved, yielding a quantum light source with a purity as high as 0.999 and a brightness reaching 6.18 × 106 cps/mW, representing a three-order-of-magnitude enhancement over bulk PPLN crystal sources. This work offers a promising solution for realizing high-brightness, high-purity on-chip quantum light sources in the mid-infrared band.
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Recent studies on orbital angular momentum (OAM) states in the surface plasmon polariton (SPP) field have primarily focused on the generation of single OAM modes and the evolution of OAM states with various topological charges. However, achieving coherent superposition of two OAM states with well-defined phase relations through precise nanostructure design remains challenging. In this work, we propose a plasmonic nanostructure consisting of paired rectangular slits arranged along circular or segmented Archimedes spiral. The Archimedean spiral of various radii in azimuthal angle provides a geometry-dependent helical phase; coupled with a rotated nanoslit pair, it introduces a geometric phase of twice the rotated angle. By combining chiral spiral with nanoslit pair units, the design both generates plasmonic OAM eigenstates with arbitrary topological charges and enables their coherent superposition. The amplitudes of the two constituent OAM states are continuously tunable through the degree of polarization of the incident light, and their relative phase difference is controlled by the polarization angle, enabling arbitrary superposition of the plasmonic OAM states with continuously variable amplitude ratios and phase differences. Theoretical analysis and numerical simulations demonstrate that circularly polarized illumination produces distinct OAM pure states, whereas linearly polarized light leads to equal-amplitude superposition states with structured field distributions. Moreover, rotating the polarization angle continuously adjusts the relative phase between the eigenstates and produces a predictable rotation of the resultant interference pattern. These results provide a new approach for coherent control of plasmonic OAM states and offer design guidelines for multifunctional on-chip optical field manipulation devices.
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Optical quantum memory plays a critical role in fields such as quantum computing, quantum sensing, and quantum communication. Cold atomic systems, owing to their excellent quantum coherence, controllability, and exceptional capability in handling weak optical fields, have emerged as one of the key platforms for faithful optical quantum state storage. Among these, cigarette-shaped, with up to 2 cm or more, cold atomic ensembles exhibit over 85 % storage effciency due to their optical depth reaching 100 or more. However, further applications are significantly hindered by the limited storage lifetimes caused by inhomogeneous residual magnetic fields along the long atomic cloud. This study analyzes the issue of atomic spin decoherence induced by non-uniform magnetic field with linear gradient, and obtain the result that storage lifetime dramatically decreases with this increasing linear gradient. Further, we demonstrate that in our two-dimensional magneto-optical trap system with a longitudinal atom-light interaction length of 2.7 cm, a DC magnetic field can provide a quantization axis, suppress the effects of inhomogeneous fields,and regulate the cycles of spin dephasing and rephasing. With the proper setting for optical pumping process of magnetic quantum levels, adjusting the pump laser power effectively controls the atomic population distribution, thereby precisely optimizes the light storage effciency at different time bins, as shown in Fig. 7(a). Based on these findings, we propose a scheme for storage of time-bin entangled photon pairs, who are prepared at two different time slots of DLCZ process. A bias magnetic field on the generation MOT (left panel of Fig. 7) induces modulation on the storage time as (a), so that read pulse exerted on rj reads only wj (j= 1, 2). Therefore, the two photonic time bins becomes distingushable and orthogonal. The retrieved photon pairs thus have fully controllable time bins for both photons. Compared to other degrees of freedom, the time encrypted photonic entanglement remains robust in long-distance network.
, , Received Date: 2025-09-10
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Al1–xScxN, as a new generation of wurtzite-type ferroelectric material, has become a focal point in ferroelectric materials research in recent years, due to its high remnant polarization, nearly ideal rectangular polarization-electric field hysteresis loops, inherent compatibility with back-end-of-line (BEOL) CMOS processes, and stable ferroelectric phase structure. The systematic and in-depth studies on the preparation, property modulation, and device applications of this material have been conducted. This paper provides a comprehensive review of the research progress of Al1–xScxN ferroelectric thin films. Regarding the factors influencing ferroelectric properties, it emphasizes the regulatory effects of Sc doping concentration on phase transition and coercive field, explores the influences of substrate (such as Si and Al2O3) and bottom electrode (such as Pt, Mo, and HfN0.4) on thin-film orientation, stress, and interface quality, and systematically summarizes the influences of deposition conditions, film thickness, testing frequency, and temperature on ferroelectric performance. At the level of physical mechanisms governing polarization switching, this review elaborates on the domain structure, domain wall motion dynamics, nucleation sites and growth mechanisms in the Al1–xScxN switching process, revealing its microscopic response behavior under external electric fields and the mechanisms underlying fatigue failure. In terms of application prospects, Al1–xScxN thin films show significant advantages in memory devices such as ferroelectric random-access memory (FeRAM), ferroelectric field-effect transistors (FeFETs), and ferroelectric tunnel junctions (FTJs). Their high performance and integration compatibility provide strong technical support for developing next-generation, high-density, low-power ferroelectric memory and nanoelectronic devices.
, , Received Date: 2025-10-15
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This work investigates the magnetocaloric effect-based green magnetic refrigeration technology, with a focus on Ni-Mn-Ga Heusler alloy as a promising magnetic refrigerant candidate. To elucidate the role of Mn-rich composition in regulating the magnetic and magnetocaloric properties, a multi-scale computational approach integrating first-principles calculations and Monte Carlo simulations is adopted. This method enables a detailed analysis of how Mn atoms occupying Ni and Ga sites influence the microstructure, atomic magnetic moments, exchange interactions, and macroscopic magnetocaloric response of the alloy. The results indicate that Mn site occupancy critically affects the magnetic performance: the occupation of Ni sites reduces the total magnetic moment and Curie temperature, thereby reducing the magnetic entropy change; in contrast, Mn occupying Ga sites significantly enhances both the total magnetic moment and the magnetic entropy change. Notably, the Ni8Mn7Ga1 alloy achieves a maximum magnetic entropy change of 2.32 J·kg–1·K–1 under a 2 T magnetic field, which significantly exceeds that of the stoichiometric Ni8Mn4Ga4 alloy. Further electronic structure analysis reveals that Mn content variation modulates the density of states near the Fermi level and optimizes orbital hybridization and ferromagnetic exchange interactions, thus adjusting the magnetic phase transition behavior. Critical exponent analysis confirms that the magnetic interactions are inherently long-range and tend toward mean-field behavior with compositional changes. By establishing a clear “composition-structure-magnetism-magnetocaloric performance” relationship on an atomic scale, this work provides theoretical foundations for designing high-performance, low-hysteresis magnetic refrigeration materials.
, , Received Date: 2025-07-09
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, , Received Date: 2025-08-29
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, , Received Date: 2025-09-04
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Multiple diagnostic techniques measured neutral gas temperatures in N2 plasma and Ar-N2 mixed plasma
, , Received Date: 2025-09-10
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Low-temperature inductively coupled radio-frequency plasma is a key plasma source in semiconductor fabrication, where the neutral gas temperature (Tg) is one of the critical parameters influencing chemical reactions and plasma characteristics. Precise control of Tg significantly influences processes such as thin-film deposition and reactive ion etching, with its synergistic interaction with plasma parameters (ne, Te) often determining process outcomes. Consequently, a thorough understanding of the evolution of Tg and its correlation with discharge parameters has become a critical issue for optimizing semiconductor manufacturing processes. To achieve more accurate measurements of neutral gas temperature, this work employs three temperature measurement techniques: spectroscopy, Bragg grating, and fiber optic sensing. These methods are used to systematically investigate the variation patterns of neutral gas temperature (Tg) in nitrogen plasma and nitrogen-argon mixed plasma under different radio-frequency power, gas pressure, and gas composition conditions. To elucidate the gas heating mechanism, this work combines Langmuir probe measurements of electron density, electron temperature, electron energy probability distribution with a global model simulation. The results show that as the RF power increases, the energy coupled to the plasma increases, the ionization reaction is enhanced, and the collision process and energy transfer between electrons and neutral particles increase, resulting in a monotonically increasing trend of Tg. When gas pressure initially increases, both electron density and background gas density rise together, enhancing heating efficiency and driving rapid Tg growth. However, beyond 3 Pa, electron mean free path shortens and electron density declines. In contrast, background gas density continues to increase, leading to slower Tg growth. In nitrogen/argon mixed system discharges, increasing the argon proportion significantly enhances the rate of Tg increase. This occurs because a higher argon ratio elevates the proportion of high-energy electrons and electron density, thereby strengthening ionization and neutral gas heating. At the same time, argon metastable atoms enhance the density of excited nitrogen particles through the Penning process, which promotes nitrogen molecular excitation to higher energy levels and further heats the gas. Additionally, we observe that the radial temperature distribution in pure nitrogen plasma shifts from parabolic to saddle-type with axial height increasing, due to intensified electron collision excitation near the coil under electromagnetic field effects. In this study, it is also found that the glass transition temperature at the radial edge remains virtually unchanged as atmospheric pressure increases. This is because, as pressure continues to rise, electrons beneath the coil struggle to migrate to the radial edge to collide with neutral particles, thereby limiting the heating of edge neutral particles.
, , Received Date: 2025-06-25
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,
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This work successfully developed a novel high-performance detector based on rare-earth-doped cesium lead chloride (CsPbCl3) inorganic scintillation crystals, targeting the critical demand for GHz-rate capabilities in ultrafast radiation detection at advanced light sources. The Ba2+-doped CsPbCl3 crystals, grown via the vertical Bridgman method, exhibit sub-nanosecond fluorescence rise times, with the pure crystal measuring ~209.6 ps and optimized doped crystals achieving ~50-75 ps. The crystals also feature nanosecond-scale decay times and enhanced light yield through defect engineering. By integrating this core scintillator with a microchannel plate photomultiplier tube (MCP-PMT) featuring sub-nanosecond transit time and a self-developed 2.5 GHz high-speed acquisition system, a complete ultrafast detection system was constructed. Rigorous testing using an optically generated equivalent GHz pulse train demonstrated that the system can clearly resolve consecutive fluorescence pulses with an average peak interval of only 0.79 ns, successfully achieving a high-repetition-rate detection capability of 1.26 GHz. Field application at the Shanghai Synchrotron Radiation Facility's soft X-ray free-electron laser (SXFEL) showed that its X-ray pulse response width is narrower than 4 ns, far superior to the >24 ns response of a reference LYSO:Ce crystal. These results validate the detector's exceptional sub-nanosecond time resolution and GHz-rate pulse discrimination, providing a reliable technical solution for ultrafast time-resolved diagnostics and photon beam loss monitoring in next-generation scientific facilities.
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The characteristics of grain boundaries (GBs) and their mechanical responses under external loading are pivotal in governing the strength and plasticity of polycrystalline ceramics. In this study, first-principles calculations were employed to investigate the stability of Σ5 {310}[001] GBs in (HfNbTaTiZr)C high-entropy carbide ceramic (HECCs) and its constituent binary transition-metal carbides (TMCs), as well as their mechanical behavior under shear and tensile deformation. The results showed that the Σ5{310}[001] GBs in all systems were classified into "Open GB" and "Compact GB" based on their morphologies, with the Open GB exhibiting lower GB formation energy and thus greater structural stability. Under shear deformation, all carbides display shear-coupled GB migration, except for the Open GBs in group IVB TMCs, where the formation of C-C bonds induces supercell failure through the rupture of TM-C bonds. Furthermore, the initial migration stress of Open GB in the HECC is higher than that in binary TMCs, highlighting the strengthening effect introduced by multicomponent GBs. Under tensile deformation, binary TMCs containing Compact GB primarily fail through graphitization, whereas the HECC exhibits both graphitization and intergranular fracture. For Open GB, group IVB TMCs yield due to increased excess volume of GB, while group VB TMCs undergo intergranular fracture; both failure mechanisms coexist in the HECC. Notably, the HECC containing Compact GBs exhibits yield strength comparable to the peak strength of binary TMCs, surpassing the "weakest-link" limit typically associated with ideal condition (0 K and defect-free). Overall, this work elucidates the synergistic roles of GB and multicomponent effects in governing mechanical responses in HECC, suggesting that the interplay between multicomponent effects and defects may underlie the exceptional mechanical performance of high-entropy materials. These findings provide theoretical guidance for GB engineering and mechanical optimization in HECCs, and they offer insights into exploring their mechanical behavior under complex defect interactions.
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