Physica Scripta

GaSb-based photocathodes is widely used in fields such as TPV, solar radiation detection due to their fast response, high long-wave sensitivity. However, thin-film structure's low absorptance is a major factor limiting their further application. We designs a photocathode with nanopillar arrays and back surface reflector structure, which can bind light to a thin active layer and significantly improve the properties of the cathode. Using the FDTD method, simulated the impact of structural parameters of the NPAs on the absorptance and emission efficiency of the active region, achieving an optimized structure with the best performance. Additionally, we discussed the effect of assistance electric field on the performance of the cathode, and found the electric-field can improve the photoelectron EQE. When the field strength exceeds 10 kV cm⁻¹, the EQE is over 18%, which is notably superior to BSR structures. Its response time in the infrared band is below 50 ps, achieving ultrafast response.

This study investigates the comparative analysis for the optoelectronic properties of zinc oxide/cerium oxide (ZnO/CeO₂) thin films prepared by e-beam evaporation and sputter deposition. A 180 nm cerium oxide (CeO₂) layer was deposited on a 370-micron silicon substrate, followed by a 150 nm zinc oxide (ZnO) layer. The bilayer films were annealed at 600 °C and 900 °C. X-ray diffraction (XRD) revealed improved crystallinity post-annealing, while scanning electron microscopy (SEM) showed morphological changes from nano fibers to nano sheets for e-beam evaporation and nano spheres for sputter deposition. The ZnO band gap decreased from 3.00 eV to 2.1 eV with annealing for e-beam evaporation and 2.70 eV to 2.10 eV with annealing for sputter deposition, showing enhanced conductivity in both un annealed and annealed films. Hall Effect measurements indicated increased mobility and resistance with higher annealing temperatures i.e. conductivity changed from 8.97 ${\rm{\times }}$ 10⁻³ to 6.68 ${\rm{\times }}$ 10⁻¹ for e-beam evaporation and 4.45 ${\rm{\times }}$ 10⁻¹ to 6.18 ${\rm{\times }}$ 10⁻¹ for sputter deposition. The study demonstrates the tailored optoelectronic characteristics of ZnO/CeO₂ thin films, with implications for materials research and electronic devices.

This research investigates the modified Benjamin-Bona-Mahony (mBBM) equation, a crucial model within nonlinear wave dynamics, which effectively characterizes long-wave propagation in dispersive media. By applying the Kumar-Malik method, the study obtains novel exact solutions to the mBBM equation, represented through diverse mathematical forms, including Jacobi elliptic, hyperbolic, trigonometric, and exponential functions. The flexibility of this approach facilitates the construction of various traveling wave solutions, including periodic, singular periodic, bright, dark, kink, anti-kink, and singular waveforms. The graphical visualization of these solutions in multiple dimensions elucidates their propagation behavior and stability, thereby reinforcing the reliability of the proposed methodology. This investigation enhances the knowledge of mathematical techniques for solving nonlinear differential equations and demonstrates their applicability to other nonlinear wave models across various scientific fields. Additionally, the findings not only provide deeper insights into the dynamics of the mBBM equation but also offer new opportunities for studying nonlinear phenomena in diverse physical systems, such as hydromagnetic waves in cold plasma, coastal engineering, nonlinear optics, fluid dynamics, plasma physics, and optical illusions. This work highlights the Kumar-Malik method as a powerful analytical tool, significantly contributing to exploring and comprehending complex wave phenomena within mathematical physics and the applied sciences.

Tunable supercontinuum generation (SCG) is reported and analyzed numerically using nematic liquid crystal infiltrated photonic crystal fiber (NLC-PCF). The optical properties of the supported modes including the nonlinearity and dispersion are controlled using an external applied voltage or temperature due to the NLC infiltration. The modal analysis of the suggested design is studied using full vectorial finite element method. The pulse propagation is then implemented using a modified nonlinear Schrödinger equation. The effects of the geometrical parameters, rotation angle and temperature on the performance of the supercontinuum generation (SCG) are investigated. The proposed NLC-PCF achieves a tunable bandwidth with broadband light spectrum. At ϕ = 90° and T = 25°C, the bandwidth of the SC spectrum is equal to 6681 nm at a length of 5 mm and λ = 1550 nm. Additionally, at ϕ = 0°, bandwidth of 11025 nm is achieved at the same device length. The reported SCG has advantages of large bandwidth and high tunability relative to those presented in the literature

The gas sensing capabilities of two-dimensional materials have been a key area of interest in nanomaterials research. In this work, the electronic and adsorption characteristics of antimonene-phosphorene nanoribbons with a 25% phosphorus composition (Sb_0.75P_0.25) for detecting CH₄ and various halomethane gases (CHCl₂F, CCl₂F₂, CH₂F₂, CH₂Cl₂, CH₃F, CH₃Cl, CH₃Br, and CH₃I) are investigated using density functional theory. The analysis reveals that all Sb_0.75P_0.25 gas-adsorbed configurations retain semiconducting properties, as indicated by the computed band structures and density of states. Notably, the adsorption of CHCl₂F, CCl₂F₂, and CH₂Cl₂ exhibits stronger interactions, characterized by more negative adsorption energies and greater charge transfer, suggesting enhanced sensitivity and selectivity of Sb_0.75P_0.25 toward these halomethanes. Additionally, applying an external electric field significantly alters charge transfer, bandgap, and adsorption energy, demonstrating the tunability of Sb_0.75P_0.25 nanoribbons for gas sensing applications. These results underscore the strong potential of Sb_0.75P_0.25-based nanosensors for efficient and selective halomethane detection, supporting their future use in advanced nanoscale sensing devices and offering insights for the experimental development of novel sensitive materials.

Additive manufacturing (AM) possesses the capacity to transform production and materials engineering by facilitating the amalgamation of dissimilar metals to create components that are lightweight, durable, and economical. This study provides a thorough analysis of the status of AM for dissimilar materials, including advantages, limitations, and diverse industrial applications. Identified key problems encompass material incompatibility, thermal stress impacts, and the development of brittle intermetallic compounds. A variety of strategies for material integration in AM are examined, including insights into material classifications, mechanical properties, industrial uses, and persistent problems. The incorporation of artificial intelligence (AI) and machine learning (ML) in augmenting the functionalities of AM is examined. This integration seeks to enhance industrial applications, forecast material behaviours, and promote the creation of innovative material combinations while addressing existing obstacles related to AI and ML integration. This paper provides a comprehensive examination of the opportunities and problems associated with the AM of heterogeneous materials, acting as a reference for future research and development initiatives to maximize the potential of this disruptive technology.

Despite their many advantages, the widespread application of magnesium (Mg) alloys is hindered by their high corrosion rates and poor ductility and formability. One effective method for enhancing both the corrosion resistance and mechanical properties, such as ductility, of Mg alloys is through alloying with Rare Earth (RE) elements. These elements have recently garnered significant attention due to their beneficial properties, including an electrode potential similar to that of Mg and their capacity to refine grain size, which contributes to reduced corrosion rates and enhanced alloy strength. This paper explores the common forms of Mg corrosion and elucidates the mechanisms by which RE elements improve corrosion resistance and mechanical behavior in Mg-RE alloys. It also provides a detailed analysis of how each RE element alters the corrosion behavior of Mg-based alloys. By integrating RE elements, it is possible to control corrosion and improve mechanical properties through mechanisms like solid solution strengthening, grain refinement, and the formation and distribution of secondary phases.

Heat transfer enhancement has become an important research area to improve the efficiency of thermal systems. This chronological review focuses on approaches for heat transfer enhancement by incorporating inputs into strategies. An in-depth review has been carried out with inserts such as twisted tapes, turbulators, vortex generators, dimple surfaces and porous materials to improve heat transfer in a variety of applications like heat exchangers, renewable energy devices, automotive systems and electronic cooling systems. A comprehensive literature review across several decades was conducted to examine the progress in improving heat transfer efficiency. Various numerical, analytical and experimental methods used in the study were examined to correct the processes and effects of different insert designs. The study includes various insert geometries, structures and materials providing a detailed analysis of the state-of-the-art in heat transfer enhancement. The review highlights key findings from studies of various inputs and their effects on heat transfer enhancement. It provides insight into efficiency metrics such as the Nusselt number, coefficient of heat transfer and pressure drop associated with each insertion method. In addition, the chronological presentation allows trends and improvements to be identified in insert-based heat transfer enhancement over the years. The results in various applications show the effectiveness of certain insert geometries and configurations in improving heat transfer performance. This chronological analysis provides a comprehensive overview of the progress in heat transfer enhancement through the use of different approaches. Knowledge gathered from various studies demonstrates the potential of insert-based methods to significantly improve the thermal conductivity of various thermal systems. Insights gained from this study can guide future research efforts, contributing to efficient and sustainable heat transfer technologies that have been developed. The conclusion highlights the importance of continued research in this area to address the growing challenges of thermal management and energy efficiency.

Two-dimensional (2D) Boron Carbon Nitride (BCN) has recently gained significant attention as a convoluted ternary system owing to its remarkable capability to exhibit a wide range of finely tunable physical, chemical, optical, and electrical properties. In this review, we discuss a variety of stable structure forms of BCN nanosheets. In addition, this review provides recent approaches for synthesizing BCN nanostructures, and properties of BCN derivatives. BCN is a promising material for sustainable energy and energy storage devices. Since BCN application is a challenge in the field of energy, we present potential applications of BCN in the field of energy including supercapacitors and batteries, wastewater treatment, electrochemical sensing, and gas adsorption.

The widespread application of synthetic dyes across industries poses significant environmental problems, particularly concerning with degradation of water quality. Concerning the possible solutions, copper oxide (CuO) considered as a feasible candidate. CuO a p-type heterogeneous semiconductor with a bandgap of 1.2–2.71 eV, It is a reasonable choice and widely studied photocatalyst for addressing such challenges. The functionality of CuO deteriorated, when the wavelength exceeded the UV–visible region. In this manner difficulties associated with reproducibility and reusability, as well as rapid electron–hole recombination, prevent the widespread application of this technology. In an attempt to eliminate this defect, researchers have been investigating strategies to activate CuO under visible light, with one promising approach being carbon nanomaterials such as graphene to form carbon-CuO composites. The unique properties of graphene, i.e., its higher surface area and excellent electron mobility, make it a remarkable candidate for the enhancement of CuO photoactivity. This study highlighted the recent progress in the synthesis of graphene-based CuO photocatalysts, with the main characteristic of extending the light absorption capacity of CuO into the visible spectrum. It reveals achievements in material innovations and applications, with a focus on photocatalytic. It has been observed from the documented studies, catalysis is considered as next generation emerging field for the researcher.

Separate spin evolution quantum hydrodynamic (SSE-QHD) model has led to a new type of spin-electron acoustic waves (SEAWs). In the present work by employing the (SSE-QHD) model we investigate the periodic structures of obliquely propagating SEAW. The nonlinear periodic wave solutions are derived by using reductive perturbation method. The periodic structures, involving both parallel and oblique propagation, are shown to exist for all permissible values of the spin polarization factor δ. However, only rarefactive periodic structures are observed in both cases. Additionally, the influence of spin polarization and obliqueness on the structure profiles is analyzed. This research could contribute to a deeper understanding of new nonlinear structures in spin-polarized plasmas.

In recent years, halide perovskites have made great progress due to their excellent optoelectronic properties. Taking advantage of the excellent elemental tunability of perovskites, a novel perovskite is designed as DAPPb₂I₆, where DAP indicates NH₃(CH₂)₅NH₃²⁺. The geometry, stability, electronic structure, and optical properties of DAPPb₂I₆ are investigated based on first principles calculations. Doping effects are taken into account by replacing I by Br. The ab initio molecular dynamics (AIMD) simulations show that these materials have high thermodynamic stability at room temperature. All DAPPb₂(I_1-xBr_x)₆ have indirect bandgaps with the calculated values of 2.21–2.71 eV, indicating that introducing of DAP increase the bandgap remarkably. The conduction bands are mainly contributed by Pb atoms, followed by halogen atoms, while the valence band part is mainly contributed by halogen atoms. These materials have high remarkable light absorption capacity with light absorption coefficients up to 4.5×10⁵ cm^-1 with wavelengths in the range of 200 - 450 nm. Doping of Br can increase the bandgap values and the cause blue-shift of the light adsorption. The newly designed DAPPb₂(I_1-xBr_x)₆ may serve as a promising wide bandgap perovskite material.

Employing Hirota's bilinear method, this investigation systematically derives multi-soliton solutions for the (3+1)-dimensional Kadomtsev-Petviashvili-Yu-Toda-Sasa-Fukuyama (KP-YTSF) equation. The introduction of innovative constraint conditions has enabled, for the first time, the observation of fission-fusion phenomena in Y-type solitons within this system. Theoretical analysis reveals that modification of these constraints induces two fundamentally distinct interaction mechanisms: (i) nonlinear coupling between Y-type solitons and single solitons, and (ii) resonant interactions between Y-type solitons and lump waves. Through advanced test function methodology, we have successfully constructed several novel analytical solutions including kink breather soliton, one soliton and lump interaction solution, and intricate interference wave solution. The development of spatiotemporal evolution models coupled with dynamic density field visualization systems has provided comprehensive characterization of the solutions' kinetic evolution properties. By integrating theoretical analysis with numerical simulations, we have achieved profound insights into both the mathematical essence and underlying physical mechanisms of these nonlinear solutions.

The aim of this study is to improve the interpolated positional accuracy of 125I seeds in brachytherapy (BT) by combining a fiber-optic dosimeter (FOD) made up of a high-Z scintillator attached to the end of a polymer optical fiber with Monte Carlo (MC) simulation techniques. The dose detection capability of the FOD is simulated and its angular response is analyzed. A source position prediction algorithm based on the signal provided by the FOD and MC simulation is proposed by simulating the dose distribution around the 125I source and the effect of multiple source dose superposition. This algorithm makes use of the genetic algorithm's optimization process and fuses the output of the FOD with the a priori knowledge base to accurately predict the source position. The validation case shows that the algorithm can effectively predict the offset position of 125I source in intertissue irradiation, which is important for improving the dose coverage accuracy and treatment effect of brachytherapy.

The coupled higher-order nonlinear Schrödinger model with variable coefficients, which can more accurately describe physical phenomena under weak nonlinear effects and provides awfully useful assistance for understanding the essence of phenomena and developing new technologies and applications, is researched drawing support from unified and improved F-expansion methods. One fairly definite fact is that the research presented in this paper has never been found before in the existing literatures. A great deal of distinct styles of solutions to the above model, such as complex solitary wave, soliton wave, elliptic wave, rational, hyperbolic trigonometric and trigonometric solutions, are reaped relying on above two techniques and corresponding mathematical software. After obtaining these valuable solutions, we analyze and study them based on 2D, 3D and contour diagrams in the case of selecting appropriate values of undetermined parameters, which conduce to deeply comprehend the connotation of the physical phenomena behind model.

We investigate a phenomenon known as Superactivation of Backflow of Information (SBFI); namely, the fact that the tensor product of a non-Markovian dynamics with itself exhibits Backflow of Information (BFI) from environment to system even if the single dynamics does not. Such an effect is witnessed by the non-monotonic behaviour of the Helstrom norm and emerges in the open dynamics of two independent, but statistically coupled, parties. We physically interpret SBFI by means of the discrete-time non-Markovian dynamics of two open qubits collisionally coupled to an environment described by a classical Markov chain. In such a scenario SBFI can be ascribed to the decrease of the qubit-qubit-environment correlations in favour of those of the two qubits, only. We further prove that the same mechanism at the roots of SBFI also holds in a suitable continuous-time limit. We also show that SBFI does not require entanglement to be witnessed, but only the quantumness of the Helstrom ensemble.

The Quantum Natural Gradient (QNG) method enhances optimization in variational quantum algorithms (VQAs) by incorporating geometric insights from the quantum state space through the Fubini-Study metric. In this work, we extend QNG by introducing higher-order integrators and geodesic corrections using the Riemannian Euler update rule and geodesic equations, deriving an updated rule for the Quantum Natural Gradient with Geodesic Correction (QNGGC). We also develop an efficient method for computing the Christoffel symbols necessary for these corrections, leveraging the parameter-shift rule to enable direct measurement from quantum circuits. Through theoretical analysis and practical examples, we demonstrate that QNGGC significantly improves convergence rates over standard QNG, highlighting the benefits of integrating geodesic corrections into quantum optimization processes. Our approach paves the way for more efficient quantum algorithms, leveraging the advantages of geometric methods.

This work demonstrated a passive mode-locked ytterbium-doped fiber laser operating at a 1-micron region. The saturable absorber incorporated was a Ti3C2Tx/MoO3 deposited on a D-shaped fiber, generating stable dissipative soliton in all normal dispersion regimes. The all-fiber ring cavity laser configuration generates mode-locked pulses with a repetition rate of 24.2 MHz, which was further verified on the radio frequency spectrum. The dissipative soliton spectrum was centered explicitly at 1031 nm with a spectral edge-to-edge bandwidth of ~3.7 nm. The Ti3C2Tx/MoO3 saturable absorber provides mode-locked stability with ~59 dB of signal-to-noise ratio. The Ti3C2Tx/MoO3 mode-locked laser was amplified up to 101 mW, corresponding to 4.1 nJ of single pulse energy.

Achieving ultra-compact, high-efficiency solar harvesting remains a central challenge in nanophotonics. Here, we demonstrate an active semiconductor nanoantenna design that dramatically enhances solar energy density through synchronized temporal modulation of its optical susceptibility. Unlike conventional passive nanoantennas, our approach uses an intensity-modulated pump laser to dynamically vary the free-electron density, creating a "plasmonic chirp" that matches the round-trip travel time of incident photons within the nanoantenna. This time-synchronized gating leads to a form of temporal trapping, which substantially increases photon confinement and absorption. Experimentally verified numerical simulations predict solar energy densities exceeding 10 GJ m⁻³—over an order of magnitude higher than standard passive designs. In addition to a comprehensive but compact numerical model, we also propose an expanded experimental platform to realize the core mechanism at scale. This work introduces a novel method for high-density solar energy harvesting at the nanoscale, with potential to significantly advance next-generation photovoltaics and optoelectronic devices.

One of the most challenging open questions in physics today is discovering the nature of dark matter. In this work we study the imaging formation in dark matter (DM) halos due to an external light source using some DM profiles for comparison with astronomical observations. Approaching these models on a small scale, we analyze the images generated on the lens plane by obtaining the analytical scaled surface mass densities Σ_*(x) and their corresponding deflection angles α_*(x), for later applying a method for ray tracing using the gravitational refraction law. The method is able to locate the positions of the images on the lens plane, by mapping fringes that represent possible sources (such as other galaxies), placed on the source plane. The regions where the strong lensing occurs for each profile, are determined by fixing the λ parameter that establishes the ray tracing process. It is shown that the presence of Einstein rings generated by each profile is directly related with the central branch of the caustic. This method gives us a possible alternative way to distinguish between different DM candidates by observing imaging from external sources.

We investigate an optical cycling scheme for Doppler cooling cold trapped ¹¹B¹⁴N⁻ ions using transitions between the X ²Σ⁺ ground state and the B ²Σ⁺ excited state, and analyze here the relevant transitions for photon cycling and repumping. Our results show that slow population decay via the first excited electronic state A ²Π cannot be neglected. To improve the optical cycling efficiency, we consider additional transitions beyond what would be expected from the highly diagonal FranckCondon factor involving the B²Σ⁺(v = 0) ← X ²Σ⁺(v = 0) transition. We estimate that the number of cycled photons alone is not likely to be sufficient to bring buffer-gas-cooled ¹¹B¹⁴N⁻ to temperatures near the Doppler cooling limit. Hence, pre-cooling, e.g., using a combination of cryogenic buffer gas and photodetachment cooling, will be essential to maximize the optical cycling efficiency and to reach a regime where Coulomb crystallization occurs. To explore pre-cooling with He or Ar buffer gases, we therefore also performed extensive quantum calculations of potential energy curves, transition moments and radiative rate coefficients for the BN⁻–buffer gas systems, to be implemented in a later study. Our results provide key insights for generating cold negative ions. These anions have, in fact, promising applications in various fields, ranging from quantum science and technology to fundamental physics and chemistry.

Alzheimer's Disease (AD) is one of the most common forms of neurodegenerative disease that involves the accumulation of amyloid beta plaques and tau tangles. The early diagnosis of AD is crucial as it helps patients to start preventive interventions to slow the disease's progression. We created a Guided-Attention Feature Extraction Deep Learning Network (GADL) for the early diagnosis of Alzheimer's disease (AD). We applied a GADL for the prediction of mild cognitive impairment (MCI) progression to AD and classification between MCI and cognitively normal (CN). We trained the model with magnetic resonance imaging images in the Alzheimer's Disease Neuroimaging Initiative (ADNI) database by subject-level data splitting and verified its generalizability in the Australian Imaging Biomarkers and Lifestyle Flagship Study of Aging (AIBL) database. Our method outperformed other subject-level studies with an accuracy of 80.29% for the prediction of MCI progression to AD and 83.70% for CN vs MCI classification in the ADNI dataset. The accuracies of our models when they were applied to the AIBL dataset are recorded as 79.38% and 79.83%, respectively. These results prove the high performance of our models in terms of its generalizability. The evaluation results showed that the proposed approach has competitive performance in comparison with recent studies in terms of its performance and generalizability. These results suggest that deep learning with guided attention can be an effective early diagnosis technique and a prognostic tool for Alzheimer's disease.

We present an experimental and theoretical study of the transport dynamics of the motion of a magnetized ball under the influence of a periodically alternating external magnetic field. The coupling between the driving field and the particle magnetic moment creates an energy reservoir that the particle uses to self-propel, while the oscillation frequency of the field, governs the rich variety of the particle patterns of motion. For each maximum amplitude of the external magnetic field considered in this study, the particle's motility dynamics exhibits different transport properties. These range from low-persistent motion at small frequencies, to a highly persistent regime at intermediate frequencies. Through theoretical analysis of the single-particle trajectories, we demonstrate control of the transport properties of the particle by tuning the frequency of the external driving field. We elucidate that for frequencies close to the characteristic frequency defined by the coupling between the ball's magnetic moment and the driving oscillating field, persistent motion emerges as consequence of the resonant dynamics. Furthermore, we develop a stochastic model that incorporates the nonlinear behavior of the angle between the ball's magnetic moment and the time-varying external magnetic field. The model generates trajectories that qualitative agree with those observed in the experiment.

The nuclear structure in the even–even ^160-180Er chain of isotopes is investigated by means of a mean-field-derived IBM-1 Hamiltonian with an intrinsic triaxial deformation derived from fermionic proxy-SU(3) irreducible representations (irreps). Energy levels and B(E2) transition strengths are calculated and compared to experimental data, where available. It is shown that the inclusion of an intrinsic triaxial deformation, stemming from the proxy-SU(3) irreps, leads to a significantly improved agreement between theoretical predictions and experimental data, compared to the axially symmetric case. The results are also compared to recent triaxial projected shell model (TPSM) and Monte Carlo Shell Model (MCSM) predictions, showing an overall good agreement, further pointing toward the preponderance of triaxiality throughout the nuclear chart.

Transparent and semi-transparent photovoltaics enable seamless integration of solar panels into building elements, thereby advancing the adoption of renewable energy utilization in the built environment without compromising design or functionality. Metamaterials can absorb a broad spectrum of light in the mid-infrared range while remaining transparent in the visible spectrum (400-800nm). This paper introduces a novel optically transparent perfect absorber (OTPA) utilizing an indium tin oxide (ITO) substrate as its foundation. The dual functionality of ITO, exhibiting strong absorption in the infrared while remaining transparent in the visible range, makes it an ideal candidate for integration into transparent solar cells (TSCs). The proposed metamaterial-based solar absorber comprises four identical square patches separated from the ITO ground plane by a Zinc Sulphide (ZnS) dielectric layer. The proposed structure employs geometrically optimized square patches to achieve broadband absorption, where nanoscale design modifications play a critical role in enhancing impedance matching and tuning resonant modes for maximum efficiency. The proposed ZnS/ITO-based Solar thermophotovoltaic (STPV) design achieves over 98% absorption in the mid-infrared spectrum (3000-14000 nm) while maintaining an average optical transmittance above 70% with a peak transmittance of 87% in the visible spectrum. Simulation results confirm broadband absorption under both transverse electric (TE) and transverse magnetic (TM) polarizations, maintaining high performance for incident angles up to 70° and polarization angles up to 90°. Infrared absorption efficiency, evaluated using the Fabry-Perot model, reveals a strong agreement with simulation results. The proposed ultrathin transparent absorber is of great potential for applications in building integrated photovoltaics (BIPV), radiative cooling and infrared imaging.