Physics Letters A最新文献

{"title":"One-photon annihilation of the bound electron-positron pair in the field of atomic nuclei","authors":"Alexei M. Frolov","doi":"10.1016/j.physleta.2025.131073","DOIUrl":"10.1016/j.physleta.2025.131073","url":null,"abstract":"<div><div>One-photon annihilation of the bound electron-positron pair in the field of atomic nuclei is investigated. In our analysis the central atomic nucleus is assumed to be an infinitely heavy, positively charged and point ‘particle’ with the electric charge <em>Qe</em>. The explicit formulas for the both annihilation cross section and one-photon annihilation rate <span><math><msubsup><mrow><mi>Γ</mi></mrow><mrow><mn>1</mn><mi>γ</mi></mrow><mrow><mo>(</mo><mi>b</mi><mo>)</mo></mrow></msubsup></math></span> are derived and discussed. We also derive and discuss the closed formula which describes the angular distribution of the emitted photons. All our formulas can directly be used to evaluate probabilities of the actual one-photon annihilation in various atoms, ions and light molecular ions which also contain one (or two) positron(s).</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131073"},"PeriodicalIF":2.6,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ab initio evaluation of the electronic and optical properties of VBCB defect in wurtzite boron nitride as promising single-photon emitter","authors":"Brandon R. McClain ,&nbsp;Sergey Stolbov ,&nbsp;Marisol Alcántara Ortigoza","doi":"10.1016/j.physleta.2025.131085","DOIUrl":"10.1016/j.physleta.2025.131085","url":null,"abstract":"<div><div>Single-photon emitters (SPEs) in the near-infrared (NIR) range with sharp and intense zero-phonon lines (ZPLs) of emission are critical for quantum communications. Certain local defects in wide-bandgap semiconductors create isolated occupied and unoccupied states within the bandgap of the host semiconductor and thus exhibit sharp ZPLs of emission. We designed and studied a defect in the wurtzite boron nitride as a potential SPE. It consists of a boron vacancy and a carbon atom substituting another boron atom (V_BC_B defect). The density of states is obtained within the GW method to identify favorable local defect states that may dominate optical transitions. The dielectric function and oscillator strength of the V_BC_B defect are obtained using the Bethe-Salpeter equation method to identify the optical excitations of the V_BC_B defect, from which we conclude that the defect could be a source of NIR emission with a narrow bright ZPL peak, thus an efficient SPE.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"564 ","pages":"Article 131085"},"PeriodicalIF":2.6,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145334469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bilayer GaN nanosheet: a potential transistor channel for next decade","authors":"Qiang Hu ,&nbsp;Hong Li ,&nbsp;Fengbin Liu ,&nbsp;Jing Lu","doi":"10.1016/j.physleta.2025.131077","DOIUrl":"10.1016/j.physleta.2025.131077","url":null,"abstract":"<div><div>Gallium Nitride (GaN) is a promising third-generation semiconductor, and H-passivated buckled bilayer GaN exhibits unique electronic characters. Bilayer GaN metal-oxide-semiconductor field-effect transistors (MOSFETs) with a 5-nm gate length are evaluated using <em>ab initio</em> quantum transport simulations. Device performance is highly sensitive to electrode doping concentrations and underlap lengths. Specifically, the best-performing <em>n</em>-/<em>p</em>-type bilayer GaN MOSFETs demonstrate on-state currents of 1059/689 and 2037/1247 µA/µm, delay times of 0.053/0.078 and 0.047/0.073 ps, and power dissipations of 0.033/0.032 and 0.057/0.054 fJ/μm for low-power and high-performance applications, respectively. These performance metrics exceed the International Roadmap for Devices and Systems (IRDS) targets for the ‘5am eq’ technology node. Notably, bilayer GaN MOSFETs outperform monolayer MoS₂, InSe, InP, silicane, and germanane in terms of on-state current under identical operating conditions. Overall, bilayer GaN offers significant advantages as a next-generation transistor channel material and is well suited for operation under extreme environmental conditions due to the intrinsic properties of GaN.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131077"},"PeriodicalIF":2.6,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neural network learning of multi-scale and discrete temporal features in directed percolation","authors":"Feng Gao ,&nbsp;Jianmin Shen ,&nbsp;Shanshan Wang ,&nbsp;Wei Li ,&nbsp;Dian Xu","doi":"10.1016/j.physleta.2025.131071","DOIUrl":"10.1016/j.physleta.2025.131071","url":null,"abstract":"<div><div>Neural network methods are increasingly applied to solve phase transition problems, particularly in identifying critical points in non-equilibrium phase transitions, offering more convenience compared to traditional methods. In this paper, we analyze the (1+1)-dimensional and (2+1)-dimensional directed percolation models using an autoencoder network. We demonstrate that single-step configurations after reaching steady state can replace traditional full configurations for learning purposes. This approach significantly reduces data size and accelerates training time. Furthermore, we introduce a multi-input branch autoencoder network to extract shared features from systems of different sizes. The neural network is capable of learning results from finite-size scaling. By modifying the network input to include configurations at discrete time steps, the network can also capture temporal information, enabling dynamic analysis of non-equilibrium phase boundaries. Our proposed method allows for high-precision identification of critical points using both spatial and temporal features.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131071"},"PeriodicalIF":2.6,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly Boosted Photoresponse Performance in α-In2Se3/WTe2 Heterobilayers: Unveiling the Type-II to Type-III Band Alignment Transition","authors":"Zhihao Qu ,&nbsp;Yinan Wang ,&nbsp;XinWei Zhao ,&nbsp;Yuhang Zhang ,&nbsp;Weiwei Zhao ,&nbsp;Fang Yang ,&nbsp;HongWei Liu","doi":"10.1016/j.physleta.2025.131076","DOIUrl":"10.1016/j.physleta.2025.131076","url":null,"abstract":"<div><div>This study unveils a transition from type-II to type-III band alignment in the α-In₂Se₃/WTe₂ van der Waals ferroelectric heterostructure under polarization switching, and demonstrates its manifestation in a giant tunneling electroresistance and a dramatically boosted photoresponse. In particular, the polarization-down (P_down) state exhibits an exceptional tunneling electroresistance ratio (TER) exceeding 10⁹, attributed to enhanced electron tunneling facilitated by the type-III band alignment. Spectroscopic analysis across 0.2–2.2 eV photon energies reveal a marked enhancement in photoresponse current under P_down polarization, particularly pronounced at low photon energies (≤1.0 eV), accompanied by remarkable polarization sensitivity (extinction ratios up to 5.85). The phenomenon electrical transport and photoresponse currents in the heterostructure, which are governed by band alignment switching and ferroelectric polarization, establish a fundamental framework for developing adaptive optoelectronic devices that integrate sensing and memory functions, and this capability presents promising potential for applications in bio-inspired artificial vision systems and photonic synapses.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131076"},"PeriodicalIF":2.6,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exact analysis of the interplay of charge order and unconventional pairings in the 2D Hatsugai-Kohmoto model","authors":"Carlos Eduardo S.P. Corsino,&nbsp;Hermann Freire","doi":"10.1016/j.physleta.2025.131070","DOIUrl":"10.1016/j.physleta.2025.131070","url":null,"abstract":"<div><div>We provide here a study of some competing ordering tendencies exhibited by the exactly solvable 2D Hatsugai–Kohmoto (HK) model on a square lattice. To this end, we investigate the interplay between superconductivity, charge-density wave (CDW) and pair-density wave (PDW) orders as a function of interaction, doping parameter, magnetic field, and uniaxial strain. As a result, we confirm the intertwined nature of CDW and PDW fluctuating orders for intermediate-to-strong couplings. We also verify that, while an applied magnetic field favors the formation of a CDW and allows the subsequent emergence of a PDW as a secondary order, strain effects favor unidirectional PDW as a primary order over the subdominant appearance of a stripe-like CDW. These results underscore the value of the HK model as an interesting platform in order to investigate (via an exactly solvable framework) the emergence of charge order and unconventional superconductivity in fermionic systems with strong interactions. Finally, we briefly discuss an orbital generalization of the HK model, which has been recently argued to be relevant to describe the properties of realistic strongly correlated systems.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131070"},"PeriodicalIF":2.6,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear dynamics of mixed traffic flow under variable speed limit control at CAV dedicated lane entrances: A macroscopic modeling approach","authors":"Guozhu Cheng ,&nbsp;Song Wang ,&nbsp;Liang Xu ,&nbsp;Yuzheng Guo ,&nbsp;Qing Wang","doi":"10.1016/j.physleta.2025.131072","DOIUrl":"10.1016/j.physleta.2025.131072","url":null,"abstract":"<div><div>This study investigates the nonlinear dynamics of mixed traffic flow near the entrance zones of dedicated connected and autonomous vehicle (CAV) lanes under variable speed limit (VSL) control. An extended macroscopic model based on the classical METANET framework is developed, incorporating the effects of dynamic speed regulation, asymmetric upstream-downstream interactions, reaction time perturbations due to sequential lane-changing maneuvers, and disturbances from ramp merging flows. A multi-objective optimization approach, integrating traffic efficiency and safety considerations, is proposed to determine the optimal VSL strategies. Numerical simulations using a microscopic traffic platform validate the model, demonstrating that the proposed VSL control effectively mitigates spatiotemporal instabilities, reduces speed variance, shortens convergence times, and suppresses lane-changing conflicts. The results reveal that traffic flow evolution in the CAV entrance zones exhibits complex nonlinear behavior analogous to nonequilibrium dissipative systems, providing new insights into macroscopic traffic control under heterogeneous driving environments.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131072"},"PeriodicalIF":2.6,"publicationDate":"2025-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A theoretical analysis of broadband nanoscale metamaterial absorber using interconnected slotted ring resonators for EMI shielding in the ultraviolet regime","authors":"Azim Sharkar ,&nbsp;Md. Al Rashed ,&nbsp;Md. Moniruzzaman ,&nbsp;Samia Larguech ,&nbsp;Saadia Binte Alam ,&nbsp;Samir Salem Al-Bawri","doi":"10.1016/j.physleta.2025.131069","DOIUrl":"10.1016/j.physleta.2025.131069","url":null,"abstract":"<div><div>This study presents a novel broadband nanoscale metamaterial absorber (MMA) designed for efficient electromagnetic interference (EMI) shielding in the ultraviolet (UV) frequency regime. The proposed structure, composed of interconnected slotted ring resonators fabricated on a silicon substrate with gold top and bottom layers, achieves exceptional absorption characteristics. It demonstrates near-unity peak absorption of 99.99 % at 824.5 THz, while maintaining &gt;85 % absorption across the operational band of 750–900 THz. Unlike conventional absorbers, the symmetrical and interconnected geometry ensures strong impedance matching, stable resonance, and polarization- as well as angle-insensitive performance, sustaining high absorption up to 90° incidence for both TE and TM modes. Detailed surface current, electric, and magnetic field analyses confirm the underlying absorption mechanisms, with antiparallel current loops inducing strong magnetic resonances that enhance energy dissipation. Parametric investigations further validate the design’s robustness, highlighting silicon as the optimal dielectric layer and identifying ideal resonator and substrate thicknesses for maximum efficiency. Importantly, the absorber exhibits negligible polarization conversion (PCR ≈ 0.00004), ensuring that incident electromagnetic energy is predominantly absorbed rather than re-radiated. Compared to existing designs, the proposed MMA offers superior absorption efficiency within a compact footprint, while also addressing the underexplored challenge of UV shielding. Given its high stability, compact size, and strong absorption, the design holds promise for applications in ultraviolet protection, biomedical device isolation, crop protection, optoelectronic systems, and stealth technologies. Overall, this work advances the development of multifunctional absorbers by combining structural simplicity with high-performance broadband absorption in the UV spectrum.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131069"},"PeriodicalIF":2.6,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual band substrate defected compact quad port MIMO antenna for 5 G MM-wave wireless communications with performance enhancement","authors":"Md Afzalur Rahman ,&nbsp;Samir Salem Al-Bawri ,&nbsp;Md. Moniruzzaman ,&nbsp;Wazie M. Abdulkawi ,&nbsp;Khair Al Shamaileh ,&nbsp;Mohammad Tariqul Islam ,&nbsp;Khaled Aljaloud","doi":"10.1016/j.physleta.2025.131058","DOIUrl":"10.1016/j.physleta.2025.131058","url":null,"abstract":"<div><div>This paper presents design and performance evaluation of a novel four-port MIMO antenna developed on a Rogers RT-5880 substrate having size of 30 × 30 × 1.6 mm³. A unique defected structure (DS) incorporating substrate defectiveness is introduced that provides -10 dB impedance bandwidth from 26.1 GHz to 32 GHz, and 35.9 GHz to 41 GHz. The DS integration leads to 1.6 GHz bandwidth enhancement at 38 GHz, alongside 3–4 dB gain enhancement. The antenna exhibits high gains of 7.5 dBi and 9.3 dBi at 28 GHz and 38 GHz, respectively. Moreover, DS enhances isolation in MIMO elements from 17 dB to 24 dB at 28 GHz and 16 dB to 23.5 dB at 38 GHz. It provides envelope correlation coefficient below 0.003 with diversity gain 10 dB. The result indicates that proposed MIMO antenna can the utilized for high-data-rate, low-latency communications, especially for 5G-enabled IoT and vehicular network applications.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131058"},"PeriodicalIF":2.6,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of low-loss and low-crosstalk compact waveguide crossing based on the adjoint method and direct binary search algorithm","authors":"Zijie Zhong ,&nbsp;Qiang Liu ,&nbsp;Jiaqi Yang ,&nbsp;Xiaoqing Wu ,&nbsp;Minming Geng ,&nbsp;Kejin Wei ,&nbsp;Zhenrong Zhang","doi":"10.1016/j.physleta.2025.131060","DOIUrl":"10.1016/j.physleta.2025.131060","url":null,"abstract":"<div><div>Mode division multiplexing technology is an important way to increase the transmission capacity of on-chip optical interconnects. Therein, multimode waveguide crossings are an important module in high-density, large-scale mode division multiplexing silicon-based photonic integrated circuits. In this paper, we designed a low insertion loss, low crosstalk, compact waveguide crossing based on the silicon-on-insulator platform. By combining the adjoint method and direct binary search method in inverse design for optimization, we achieved a compact, high-performance three-mode (TE₀, TE₁ and TE₂) waveguide crossing, with a total footprint only 7.5 μm × 7.5 μm. Simulation results show that the designed waveguide crossing exhibits low insertion loss (&lt;0.78 dB) and low crosstalk (&lt;-27 dB) in the wavelength range from 1510 nm to 1590 nm. At 1550 nm wavelength, the insertion losses for the TE₀, TE₁ and TE₂ modes are 0.15 dB, 0.37 dB, and 0.65 dB respectively and the corresponding crosstalk can reach -40 dB.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"563 ","pages":"Article 131060"},"PeriodicalIF":2.6,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}