bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced polarization and endurance properties of ZrO2-based ferroelectric capacitor using HfO2 interfacial layer
Authors: Zhang Wei , Shi Yuxuan , Zhang Bowen , Liu Zengqiang , Cao Yating , Pan Ting , Li Yubao 
Published: July 2024

Abstract
Recently discovered ferroelectricity in fluorite-structure ZrO2 thin film has attracted increasing and intense interest due to its lower crystallization temperature and higher content in nature in comparison to hafnium oxide. Here, the effect of HfO2 interfacial layer on the ferroelectric properties of ZrO2 thin films is investigated systematically by designing four types of interfacial structures. It is revealed that the ferroelectric orthorhombic phase, remanent polarization, and endurance can be improved in ZrO2 thin film by inserting both a top- and bottom-HfO2 interfacial layer. A maximal ferroelectric remanent polarization (2P
r) of 53.4 μC cm−2 and an optimal endurance performance of 3 × 107 field cycles under frequency of 100 kHz are achieved in Pt/HfO2/ZrO2/HfO2/Pt capacitors, with ferroelectric stacks being crystallized at 450 °C via post-deposition annealing method. X-ray photoelectron spectroscopy analysis confirms that the HfO2 bottom-layer plays a very important role in the formation of a higher ratio o-phase, thus enhancing the ferroelectricity. These results suggest that designing appropriate interfaces would help achieve excellent ferroelectric properties in ZrO2 films.
Response and resilience of carbon nanotube micropillars to shear flow
Authors: Julien Brandon N , Jeon Minae , Geranfar Erfan , Ghode Rohit G S , Boutilier Michael S H 
Published: July 2024

Abstract
Interactions between carbon nanotubes (CNTs) and fluid flows are central to the operation of several emerging nanotechnologies. In this paper, we explore the fluid-structure interaction of CNT micropillars in wall-bounded shear flows, relevant to recently developed microscale wall shear stress sensors. We monitor the deformation of CNT micropillars in channel flow as the flow rate and wall shear stress are gradually varied. We quantify how the micropillars bend at low wall shear stress, and then will commonly tilt abruptly from their base above a threshold wall shear stress, which is attributed to the lower density of the micropillars in this region. Some micropillars are observed to flutter rapidly between a vertical and horizontal position around this threshold wall shear stress, before settling to a tilted position as wall shear stress increases further. Tilted micropillars are found to kink sharply near their base, similar to the observed buckling near the base of CNT micropillars in compression. Upon reducing the flow rate, micropillars are found to fully recover from a near horizontal position to a near vertical position, even with repeated on–off cycling. At sufficiently high wall shear stress, the micropillars were found to detach at the catalyst particle-substrate interface. The mechanical response of CNT micropillars in airflow revealed by this study provides a basis for future development efforts and the accurate simulation of CNT micropillar wall shear stress sensors.
III-V material-based junction-free L-shaped gate normal line tunneling FET for improved performance
Authors: Anam Aadil , Amin S Intekhab , Prasad Dinesh 
Published: July 2024

Abstract
In this paper, we introduce a novel III–V compound material-based junction-free (JF) L-shaped gate normal line tunneling field-effect transistor (III–V JF L GNLTFET) for improved output performance at 0.5 V operation. The key design metric, i.e. JF or junctionless design, in our device eliminates issues like random dopant fluctuations (RDF) and high thermal budgets and streamlines the fabrication. The implementation of III–V compound material, i.e. low bandgap compound GaSb, in the source region, combined with the larger area gate normal line tunneling, improves the ON current for our proposed III–V JF L GNLTFET device. Additionally, the utilization of large bandgap GaAs compounds on the drain and channel sides eliminates ambipolarity and further enhances the performance of our proposed device. Meaning that the proposed device simultaneously improves the ON current and suppresses the ambipolarity. Our proposed III–V JF L GNLTFET exhibits enhanced output performance with an ON current of 23.2 μA μm−1 and a minimum and average subthreshold swing of 3.7 mV dec−1 and 15.82 mV dec−1 respectively. Furthermore, the proposed III–V JF L GNLTFET also gives superior RF/analog performance with transconductance (168.65 μS), cut-off frequency (33.52 GHz), gain-bandwidth product (5.11 GHz), and transconductance-frequency product (243.7 GHz).
Intensive study on gamma-irradiated PVA/FeCl3/NiO nanocomposites for promising applications: structural, optical and electrical
Authors: Zaghlool R A , ElShawadfy S R , Mohamed F , Abdel Moghny A S 
Published: July 2024

Abstract
Tuning the optical parameters as well as the electrical conductivity of polymer composites is required to match the needs of optical and/or electrolyte-based energy storage devices. Depending on the choice of filler, the addition of small amounts of inorganic fillers to suitable polymers allows this target to be attained. In the present study, polyvinyl alcohol (PVA)/FeCl3/xNiO nanocomposites were prepared using the solution cast method. The structural, optical and electrical properties were investigated before and after irradiating the nanocomposites with gamma radiation at two doses, 300 and 400 Gy. Fourier transform infrared analysis confirmed the interaction of NiO with the PVA/FeCl3 matrix. The nanocomposites show a direct band gap that decreases from 2.47 to 2.25 eV as the NiO content increases from 0% to 7%, while the dc conductivity is increased from 9.15 × 10−8 to 8.46 × 10−7 S cm−1. After irradiation by 400 Gy of gamma radiation, the band gap of the PVA/ FeCl3/7%NiO nanocomposite is increased to 2.33 eV while the dc conductivity decreases to 1.19 × 10−8 S cm−1. On the other hand, the PVA/FeCl3 matrix shows low refractive index, 1.134 at 550 nm, which further increases to 1.213 as the NiO content reaches 7 wt%; this is reduced to 1.211 after exposure to 300 Gy of gamma radiation.
A novel numerical approach for analyzing experimental data on critical current degradation in Nb3Sn wires caused by transverse deformations preceding heat treatment
Authors: Burioli S , Iannone G , De Marzi G , D’Agostino D , Avallone G , Gagno A , Bracco M , Leveratto A , Traverso A , Pedrini D , Valente R , Prioli M , Piccardo P , Malagoli A , Farinon S , Musenich R 
Published: July 2024

Abstract
In the framework of studies on high-field magnets for future accelerators, a specific project called ASTRACT focuses on the effect of transverse strain on the critical current of Nb3Sn wires. The first phase of the project addresses the effects of strain imposed on Nb3Sn wires before heat treatment and the development of a procedure to directly compare critical current measurements with values extracted from magnetization cycles. A Nb3Sn RRP-Ti wire was deformed to different values of transverse strain (10%, 15%, 20%, and 25%), and long samples were collected for transport measurements at 4.2 K, in a background field ranging from 10 to 14 T. Short samples were used for magnetization measurements (VSM technique). Additionally, SEM images of the cross-section were collected at different longitudinal positions along the wire for each strain value. This paper proposes a method based on SEM image analysis and magnetization measurements analysis to study the effect of bundle deformation on transport properties. The procedure requires morphological information provided by SEM images after appropriate numerical processing. Verification through statistical comparison between the Ic transport and VSM data is also conducted. Direct critical current measurements showed no degradation due to deformation up to 25%. The method introduced, independent of transport data, can reach the same conclusions by considering the real shape of the bundles.
Enhancing the magnetic field gradient between two superconductors with rotational motion under a background DC field
Authors: Houbart M , Fagnard J-F , Harmeling P , Dular J , Dennis A R , Namburi D K , Durrell J H , Geuzaine C , Vanderheyden B , Vanderbemden P 
Published: July 2024

Abstract
The ability of bulk high-temperature superconductors to trap magnetic flux densities up to one order of magnitude larger than the saturation magnetization of conventional ferromagnetic materials offers the prospect of generating large magnetic flux density gradients. Combining multiple superconductors, akin to assembling a Halbach array of permanent magnets, may increase the generated gradient even further. The associated challenge is that superconductors are prone to demagnetization when exposed to field components perpendicular to their main magnetization direction. In the present work, we investigate the magnetic flux density gradient achieved with a pair of cubic, bulk, large-grain melt-textured superconductors in the presence of a background DC magnetic field at 77 K. We investigate the increase of the performance when decreasing the temperature down to 59 K. The studied configuration consists in two facing cubic YBa2Cu3O

7
−
x

superconductors of 6 mm side with anti-parallel magnetization directions. It is obtained after the simultaneous magnetization of the samples followed by a rotation of 180∘ of the top superconductor. Although the background field reduces the trapped field ability of individual samples, it is shown that this phenomenon is significantly mitigated at 65 K and at 59 K compared to 77 K. The results reveal that a sample-to-sample distance (

∼

16

mm) of the order of their size is sufficient to avoid any mutual demagnetization effect during the rotational motion. Furthermore, it is shown that decreasing the temperature is not only beneficial in increasing the field and field gradient achieved but also in extending the range of background fields in which the superconductor can be rotated without demagnetization. This superconducting assembly yields a magnetic flux density gradient exceeding that of an isolated superconductor and has the potential to surpass the capabilities of permanent magnets.
Understanding different oxidation methods for the hole transport layer Spiro-OMeTAD to improve perovskite solar cell performance
Authors: Chen Xinyao , He Linfeng , Zhang Chunqian , Cheng Jin , Liu Yuan , Li Junming 
Published: July 2024

Abstract
The preparation of a high-performance hole transport layer is a pivotal factor in achieving efficiency and stable perovskite solar cells. 2,2’,7,7’-Tetrakis[N, N-di(4-methoxyphenyl)amino]−9,9’-spirobifluorene (Spiro-OMeTAD) currently stands as the most widely employed hole transport material in high-performance perovskite solar cells. The current methodologies for its preparation primarily revolve around three techniques: O2 oxidation, cobalt salt doping, and CO2 bubbled doping. In this study, we systematically investigated and analyzed Spiro-OMeTAD prepared through these three methods, from solution and film to device. The CO2-bubbled method and Co-doped method allow for faster and more complete oxidation of Spiro-OMeTAD while maintaining conductivity and energy level matching. Therefore, the film of both methods shows better carrier extract capabilities and defect states than that of O2-oxidized. In particular, the film of the CO2-bubbled method had better hydrophobicity and thermal stability, showing the least degradation at 85 °C annealing, which can be attributed to the removal of hydrophilic Li+. This study could inspire further optimization of Spiro-OMeTAD film fabrication processes in perovskite solar cells.
Numerical simulation of arc stabilizing cycle in vacuum arc remelting of titanium alloy
Authors: Li Mingyu , Jia Lei , Miao Qingdong , Liu Wei , Zhao Peng , Yang Shufeng 
Published: July 2024

Abstract
Through utilizing numerical simulation methods, the flow state of the molten pool during the vacuum self-consumption melting process of titanium alloy was analyzed. The influence of the stable arc cycle on the shape of the molten pool, dendrite arm spacing, surface quality, and shrinkage cavity was examined. The results showed that without an external magnetic field, the molten pool for smelting a Φ720 mm specification titanium alloy ingot is dominated by self-inductance magnetic force, leading to a downward flow in the central part of the melt. A mere 0.5 G stray magnetic field can result in Ekman pumping, causing an upward secondary flow in the core to counteract it. At an externally added magnetic field strength of 50 G, choosing a 10 s-20 s cycle can achieve a relatively stable double loop flow pattern. The shape of its molten pool, dendrite arm spacing, and contact ratio all reach optimal performance, thus verifying the possibility and feasibility of the double loop flow, and the macroscopic segregation of the simulated ingots essentially matches the experimental results, aiming to provide references for selecting parameters in actual production.
Accretion onto oscillating cosmic string loops
Authors: Jiao Hao , Cyr Bryce , Brandenberger Robert 
Published: July 2024

Abstract
Cosmic string loops are non-linear density fluctuations which form in the early universe and could play an important role in explaining many phenomena which are in tension with the standard ΛCDM model. Hence, the accretion process onto cosmic string loops should be studied in detail. Most previous works view loops as point masses and ignore the impact of a finite loop size. In this work, we utilize the Zel'dovich approximation to calculate the non-linear mass sourced by a static extended loop with a time-averaged density profile derived from the trajectory of the loop oscillation, and compare the result with what is obtained for a point-mass source. We find that the finite size of a loop mainly affects the evolution of turnaround shells during the early stages of accretion, converging to the point mass result after a critical redshift, zc
( II)/( III). For zc
( II)/( III), the total accreted mass surrounding a loop is suppressed relative to the point mass case and has a growth rate proportional to (1+z)-3/2.
As an immediate extension, we also qualitatively analyse the accretion onto moving point masses and onto moving extended loops. In addition to the reduction in the nonlinear mass, the loop finite size also changes the shape of the turnaround surface at early stages of accretion.
Searching for QPOs in BATSE short gamma-ray bursts based on narrowband and broadband features
Authors: Liu Dong-Jie , Zou Yuan-Chuan 
Published: July 2024

Abstract
Gamma-ray bursts (GRBs), especially short GRBs, are often considered potential candidates for exhibiting kilohertz quasi-periodic oscillations (QPOs) due to their origin from binary mergers. It has already been discovered that two bursts exhibit QPOs. While systematic searches for QPOs in GRBs typically concentrate on the kilohertz range, there has been no comprehensive exploration in the hundred-hertz range. In this study, we systematically conducted QPO searches on all BATSE short burst data within the 0-1000 Hz range. Using nested significance tests, we observed that the reference distributions for different GRBs are quite similar. This observation prompted us to analyze the data by selectively focusing on those with larger statistical values, obviating the need to iterate through all the data and significantly reducing computational workload. Ultimately, our findings did not reveal any compelling evidence for QPOs, which may suggest that the GRB jet has lost the early merging memory.
Observational test of ℛ2spacetimes with the S2 star in the Milky Way galactic center
Authors: Yan Jian-Ming , Zhu Tao , Azreg-Aïnou Mustapha , Jamil Mubasher , Nguyen Hoang Ky 
Published: July 2024

AbstractA novel class of vacuum metrics expressible in analytical form was recently found for pure ℛ2gravity, based on a groundwork put forth by Buchdahl in 1962. These Buchdahl-inspired solutions offer a practical framework for testing ℛ2gravity through empirical observations. Within a subclass of asymptotically flat Buchdahl-inspired vacuum spacetimes, we identified a parameter ϵ measuring the deviation from the classic Schwarzschild metric, which corresponds to ϵ=0. In this paper, we employ observational data from the S2 star's orbit around Sgr A* in the Milky Way galactic center and perform Monte Carlo Markov Chain simulations to probe the effects of the new metrics on the orbit of the S2 star. Our analysis presented herein reports a range at 95% confidence level on the deviation parameter as ϵ ∈ (-0.6690, 0.4452). While no decisive evidence either in favor or in disfavor of the asymptotically flat Buchdahl-inspired spacetimes has been achieved, the obtained bound is compatible with the tighter results using other data of different nature as recently reported inEur. Phys. J. C84(2024) 330. As a meaningful test probing into a strong-field regime, our present study calls for further observations with prolonged period and improved accuracy in order to tighten the bound for ϵ using the S2 star orbit.
Enhanced curvature perturbation and primordial black hole formation in two-stage inflation with a break
Authors: Wang Xinpeng , Zhang Ying-li , Sasaki Misao 
Published: July 2024

AbstractWe investigate a model of R2-gravity with a non-minimally coupled scalar field that gives rise to two-stage inflation with a break, that is, with an intermediate stage where inflation momentarily halts. We find that the power spectrum of the primordial curvature perturbation is significantly enhanced at the break scale, which can account for the primordial black hole (PBH) formation, without affecting the CMB constraint on large scales. The behavior of the curvature perturbation is carefully analyzed and we find a few notable new features in the spectrum. In particular, we find that the k3growth of the spectrum of toward the end of the first stage of inflation. We argue that this is a universal feature common to all two-stage models where the field dominating the second stage is heavy during the first stage. By appropriately tuning the model parameters, we find that our model can realize the scenario of PBHs as the cold dark matter of the Universe. We also find that we can choose the parameters so that the spectrum of the induced gravitational waves from the enhanced curvature perturbation fits the NANOGrav-15yr data of pulsar timing array observation.
Simulation study of multi-layer titanium nitride nanodisk broadband solar absorber and thermal emitter
Authors: Huang Xi , Yi Yingting , Song Qianju , Yi Zao , Ma Can , Tang Chaojun , Zeng Qingdong , Cheng Shubo , Raza Rizwan 
Published: July 2024

Abstract
Solar energy has always been a kind of energy with large reserves and wide application. It is well utilized through solar absorbers. In our study, the finite difference time domain method (FDTD) is used to simulate the absorber composed of refractory metal materials, and its absorption performance and thermal emission performance are obtained. The ultra-wide band of 200 nm–3000 nm reaches 95.93% absorption efficiency, of which the bandwidth absorption efficiency of 2533 nm (200 nm–2733 nm) is greater than 90%. The absorption efficiency in the whole spectrum range (200 nm–2733 nm) is 97.17% on average. The multilayer nanodisk structure of the absorber allows it to undergo strong surface plasmon resonance and near-field coupling when irradiated by incident light. The thermal emission performance of the absorber enables it to also be applied to the thermal emitter. The thermal emission efficiency of 95.37% can be achieved at a high temperature of up to 1500 K. Moreover, the changes of polarization and incident angle do not cause significant changes in absorption. Under the gradual change of polarization angle (0°–90°), the absorption spectrum maintains a high degree of consistency. As the incident angle increases from 0° to 60°, there is still 85% absorption efficiency. The high absorption efficiency and excellent thermal radiation intensity of ultra-wideband enable it to be deeply used in energy absorption and conversion applications.
On examining the predictive capabilities of two variants of the PINN in validating localized wave solutions in the generalized nonlinear Schrödinger equation
Authors: Thulasidharan K , Sinthuja N , Priya N Vishnu , Senthilvelan M 
Published: July 2024

Abstract
We introduce a novel neural network structure called strongly constrained theory-guided neural network (SCTgNN), to investigate the behaviour of the localized solutions of the generalized nonlinear Schrödinger (NLS) equation. This equation comprises four physically significant nonlinear evolution equations, namely, the NLS, Hirota, Lakshmanan–Porsezian–Daniel and fifth-order NLS equations. The generalized NLS equation demonstrates nonlinear effects up to quintic order, indicating rich and complex dynamics in various fields of physics. By combining concepts from the physics-informed neural network and theory-guided neural network (TgNN) models, the SCTgNN aims to enhance our understanding of complex phenomena, particularly within nonlinear systems that defy conventional patterns. To begin, we employ the TgNN method to predict the behaviour of localized waves, including solitons, rogue waves and breathers, within the generalized NLS equation. We then use the SCTgNN to predict the aforementioned localized solutions and calculate the mean square errors in both the SCTgNN and TgNN in predicting these three localized solutions. Our findings reveal that both models excel in understanding complex behaviour and provide predictions across a wide variety of situations.
Comparison of photon interaction coefficients for tumor compositions and healthy tissues simulated by Monte Carlo
Authors: Bozkurt Ahmet , Sengul Aycan 
Published: July 2024

Abstract
This study compares interaction coefficients of photons
(namely, mass attenuation, energy absorption and energy transfer
coefficients) for some tumor tissues with simlar healthy
tissues. Monte Carlo calculations were performed for adenoidcystic
carcinoma, melanoma, rectal adenocarcinoma, sarcoma and squamous
cell lung carcinoma. The simulation model involved a monoenergetic
point source producing a pencil beam. Depending on the parameter
under study, average flux, energy flux, or dose deposition from
photons that travels in an absorber were scored in the range of
10 keV–20 MeV energy using MCNP6.1. The same model was used to
compute the interaction coefficients of health tissues (namely,
gastrointestinal tract-small intestine wall, lungs-parenchyma,
salivary glands, skin, soft tissue (female+male)) for comparison
purposes. The results showed that, depending on the contents of the
tumor samples, photon interaction coefficients of a tumor may differ
from those of a similar healthy tissue. This behavior was distinct,
especially for energies up to 100 keV, and was attributed to the
presence of relatively higher atomic number elements in the
absorber.