bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric instability in the neutron star extreme matter observatory
Authors: Pan Juntao , Zhang Jue , Blair Carl , Jones Aaron W , Zhao Chunnong , Ju Li 
Published: March 2022

Abstract
Parametric instability (PI), induced by the interaction between the cavity optical modes and acoustic modes of a mirror, is an inherent risk in interferometric gravitational wave detectors. The instability can result in exponential growth in acoustic mode amplitude and the saturation of detectors control systems. In this paper we analyse PI in the neutron star extreme matter observatory, a proposed high optical power (4.5 MW) detector, operating at cryogenic temperatures with silicon test masses (TMs), targeting high sensitivity between 1 and 4 kHz. Our results show that with current design parameters, approximately 16 unstable modes will arise per TM with maximum parametric gain ∼10. Varying the TM radius of curvature from the nominal values could eliminate PI, however not with current manufacture or actuator capability. PI mitigation will be required to suppress all unstable modes. This analysis identifies four optical modes and 16 acoustic modes dominating PI in NEMO paves the way for the design of PI mitigation strategies.
The spectroscopic ellipsometry measurement of non-polar freestanding GaN: comparison between isotropic and anisotropic models
Authors: Wang Yakun , Xu Gengzhao , Han Sha , Chen Kebei , Zhang Chunyu , Song Wentao , Wang Jianfeng , Liu Zhenghui , Xu Ke 
Published: March 2022

Abstract
For anisotropic materials, the pseudo-dielectric function (DF) from isotropic model is often applied in spectroscopic ellipsometry data analysis instead of the DF from anisotropic model because of its simplicity. Whether this approximation is applicable depends on the discrepancy between the pseudo-DF and the DF, which we find to be related to the illumination configuration greatly. For the ellipsometry spectra obtained from a non-polar freestanding GaN in two configurations with the c-axis perpendicular and parallel to the incident plane respectively, both anisotropic model and isotropic model are used to compare the difference between the fitted absorption coefficient and pseudo-absorption coefficient. As a consequence, the discrepancy between the two coefficients is less than 10

%

even at the absorption edge when electric field is perpendicular to the c-axis, while the discrepancy exceeds 40

%

at the absorption edge when electric field is parallel to the c-axis. These results indicate that the approximation of using isotropic model instead of anisotropic model is reasonable in the former configuration, while it is not applicable in the latter configuration and will render an overestimation of bandgap. The above two different discrepancies could be explained by the first-order term approximation of pseudodielectric function. We further demonstrate the necessity for anisotropic model by comparing the deviations of the crystal-field splitting obtained from anisotropic and isotropic model with the theoretical value respectively.
Valley polarized transport and negative differential resistance in an irradiated

α−T3

lattice
Authors: Niu Zhi Ping , Wang Shuo Jun 
Published: March 2022

Abstract
In this work, we study the valley dependent current in an

α
−

T

3

lattice based device via the non-equilibrium Green’s function method. The influences of off-resonant circularly polarized light on band structures and current–voltage characteristics are investigated. In the presence of circularly polarized light, the band structures, particularly in the flat band, are distorted, and the valley degeneracy is broken, causing the current valley to be polarized. If the circularly polarized light only irradiates the right electrode, one valley is forward conducting but backward blocking, and the opposite is valid for the other valley; thus a bipolar valley diode effect is demonstrated. When the light’s handedness is reversed, the valley indexes of the currents are swapped. If the circularly polarized lights irradiate both electrodes, by reversing the light’s handedness the device can be switched between an ‘on’ state, with a 100% valley polarized current and an ‘off’ state. Interestingly, negative differential resistance is observed, becoming more pronounced as α decreases. The features reported here make the

α
−

T

3

lattice ideal for future valleytronics applications.
Tunable magnetic and magnetotransport properties in locally epitaxial La0.67Sr0.33MnO3 thin films on polycrystalline SrTiO3, by control of grain size
Authors: Dallocchio Marie , Boileau Alexis , Mercey Bernard , David Adrian , Lüders Ulrike , Froissart Sandrine , Larose Xavier , Bérini Bruno , Dumont Yves , Pautrat Alain , Prellier Wilfrid , Fouchet Arnaud 
Published: March 2022

Abstract
La0.67Sr0.33MnO3 (LSMO) thin films have been grown by pulsed laser deposition on SrTiO3 using combinatorial substrate epitaxy (CSE) approach, i.e. polycrystalline substrates with micrometer-size grains. The crystallographic domains size of those polycrystalline substrates can be controlled between 2 and 45 µm depending on the annealing temperature during synthesis. Each grain of the substrate acts as a single crystalline growth template promoting local epitaxy with a reproduction of the substrate grain structure in the thin film. Therefore, a fine-tuning of the substrate grain metrics and high crystalline quality of locally epitaxial LSMO film, allows to combine the advantages of polycrystalline, i.e. the presence of low field magnetoresistance (LFMR) and the possibility to use very thin films, with a pronounced magnetic shape anisotropy. For this, the magnetic and transport properties of the films are showing a strong influence with varying grain metrics of the substrate. High Curie temperatures, important values of the LFMR and anisotropy for optimized substrate grain metrics with the relative orientation of the magnetic field to the film plane underline the high quality of the films and the advantage of the CSE approach. The obtained LSMO thin films may have an interest for high-resolution low field magnetic sensors application.
Quantifying transfer learning synergies in infinite-layer and perovskite nitrides, oxides, and fluorides
Authors: Sahinovic Armin , Geisler Benjamin 
Published: March 2022

Abstract
We combine density functional theory simulations and active learning (AL) of element-embedding neural networks (NNs) to explore the sample efficiency for the prediction of vacancy layer formation energies and lattice parameters in ABX

n
infinite-layer (n = 2) versus perovskite (n = 3) nitrides, oxides, and fluorides in the spirit of transfer learning. Following a comprehensive data analysis from different thermodynamic, structural, and statistical perspectives, we show that NNs model these observables with high precision, using merely

∼
30
%

of the data for training and exclusively the A-, B-, and X-site element names as minimal input devoid of any physical a priori information. Element embedding autonomously arranges the chemical elements with a characteristic recurrent topology, such that their relations are consistent with human knowledge. We compare two different embedding strategies and show that these techniques render additional input such as atomic properties negligible. Simultaneously, we demonstrate that AL is largely independent of the initial training set, and exemplify its superiority over randomly composed training sets. Despite their highly distinct chemistry, the present approach successfully identifies fundamental quantum-mechanical universalities between nitrides, oxides, and fluorides that enhance the combined prediction accuracy by up to 16% with respect to three specialized NNs at equivalent numerical effort. This quantification of synergistic effects provides an impression of the transfer learning improvements one may expect for similarly complex materials. Finally, by embedding the tensor product of the B and X sites and subsequent quantitative cluster analysis, we establish from an unbiased artificial-intelligence perspective that oxides and nitrides exhibit significant parallels, whereas fluorides constitute a rather distinct materials class.
Molecular dynamics simulations of tensile mechanical properties and microstructures of Al-4.5Cu alloy: the role of temperature and strain rate
Authors: Wang Mingjie , Huang Xixi , Wu Shiping , Dai Guixin 
Published: March 2022

Abstract
In this paper, the deformation behavior of Al-4.5Cu alloys containing the Cu clusters under high temperature is systematically investigated by molecular dynamics. Reduced nucleation stress of dislocation is driven by increasing strain rate and temperature, which triggers the stress–strain curves of Al-4.5Cu alloy showing gradually elastic-plastic stage and elastic-plastic-viscous stage. Besides, the defect surface in Al-4.5Cu alloy do not have enough time to move along and gather due to the increase of strain rate, which make the distribution of defect surface mainly divide into three types: the plane distribution which is at 45° angle to the direction of tensile, the stratification distribution which is perpendicular to the direction of tensile and the distribution of honeycomb, respectively. The microscopic fracture morphology for Al-4.5Cu alloy are changed from pure shear fracture to microporous aggregate fracture due to three type of defect surface.
A first principles investigation of ternary and quaternary II–VI zincblende semiconductor alloys
Authors: Mannodi-Kanakkithodi Arun 
Published: March 2022

Abstract
One of the most common ways of tuning the stability, electronic structure, and optical behavior of semiconductors is via composition engineering. By mixing multiple isovalent elements at any cation or anion site, new compositions may be generated with markedly different properties than end-point compositions, and not always lying within a predictable trend. In this work, we explore the trends in lattice constant, electronic band gap, formation and mixing energy, and optical absorption behavior in a series of II–VI zincblende semiconductors with Cd/Zn at the cation site and S/Se/Te at the anion site, using multiple levels of density functional theory approximations. We find that while the GGA-PBE functional reproduces all trends correctly, full geometry optimization with the HSE06 functional predicts band gaps with much higher experimental accuracy. We find that all mixed S–Se and mixed Cd–Zn compounds show linear trends in band gap, rising from Se to S and Cd to Zn, respectively, whereas all Se–Te mixed compounds exhibit band gap bowing. All mixing energy curves, calculated based on decomposition to end point compositions, show inverted bowing behavior but with small positive mixing energy values <50 meV per formula unit, indicating robust stability of all solid solutions. Formation energies, calculated based on decomposition to elemental species, always show linear trends and remain sufficiently negative for all binaries, ternaries and quaternaries, whereas lattice constants show expected linear trends. We further report trends in optical absorption spectra and relationships between PBE and HSE computed properties, which reveal equations that can be used to accurately predict higher fidelity data. This work lays out systematic trends in the stability and optoelectronic characteristics of Cd–Zn–S–Se–Te alloys and enables the selection of optimal compositions for desired applications.
Increasing the structural and compositional diversity of ion-track templated 1D nanostructures through multistep etching, plastic deformation, and deposition
Authors: Hossain U H , Jantsen G , Muench F , Kunz U , Ensinger W 
Published: March 2022

Abstract
Ion-track etching represents a highly versatile way of introducing artificial pores with diameters down into the nm-regime into polymers, which offers considerable synthetic flexibility in template-assisted nanofabrication schemes. While the mechanistic foundations of ion-track technology are well understood, its potential for creating structurally and compositionally complex nano-architectures is far from being fully tapped. In this study, we showcase different strategies to expand the synthetic repertoire of ion-track membrane templating by creating several new 1D nanostructures, namely metal nanotubes of elliptical cross-section, funnel-shaped nanotubes optionally overcoated with titania or nickel nanospike layers, and concentrical as well as stacked metal nanotube-nanowire heterostructures. These nano-architectures are obtained solely by applying different wet-chemical deposition methods (electroless plating, electrodeposition, and chemical bath deposition) to ion-track etched polycarbonate templates, whose pore geometry is modified through plastic deformation, consecutive etching steps under differing conditions, and etching steps intermitted by spatially confined deposition, providing new motifs for nanoscale replication.
Enhancement of lateral Casimir force on a rotating particle near hyperbolic metamaterial
Authors: Wang Tong-Biao , Zhou Ying , Mu Hong-Qian , Shehzad Khurram , Zhang De-Jian , Liu Wen-Xing , Yu Tian-Bao , Liao Qing-Hua 
Published: March 2022

Abstract
Enhancement of weak Casimir forces is extremely important for their practical detection and subsequent applications in variety of scientific and technological fields. We study the lateral Casimir forces acting on the rotating particles with small radius of 50 nm as well as that with large radius of 500 nm near the hyperbolic metamaterial made of silicon carbide (SiC) nanowires. It is found that the lateral Casimir force acting on the small particle of 50 nm near hyperbolic metamaterial with appropriate filling fraction can be enhanced nearly four times comparing with that acting on the same particle near SiC bulk in the previous study. Such enhancement is caused by the coupling between the resonance mode excited by nanoparticle and the hyperbolic mode supported by hyperbolic metamaterial. The results obtained in this study provide an efficient method to enhance the interaction of nanoscale objects.
Fabrication of highly sensitive and uniform Ag/PS/PDMS SERS substrate and its application for in-situ detection
Authors: Xu Guangming , Shen Xilong , Zhang Lei , Tang Jie , He Chuan , Zhou Ziqiang , Xu Tian , Xu Meifeng , Jin Yonglong , Wang Chaonan 
Published: March 2022

Abstract
In this study, we developed a flexible and transparent silver/polystyrene/polydimethylsiloxane (Ag/PS/PDMS) substrate with both high density of hot spots and satisfactory uniformity using a cost-effective approach. Via template-guided self-assembly, PS beads were arranged regularly in nanobowls of a square array on PDMS, whose surface structure was transferred from a commercial complementary metal oxide semiconductor chip. Roughness was introduced onto the PS bead surface by nitrogen plasma treatment, followed by sputtering of Ag which generated many hot spots. Differential roughness on the PS bead surface greatly influenced the morphology of the Ag/PS/PDMS substrate. A meat-ball like surface structure was formed with a plasma etching time of 5 min, whose growth mechanism was proposed based on the scanning electron microscope analysis. The high sensitivity and desirable uniformity of the meat-ball like Ag/PS/PDMS substrate were demonstrated by using crystal violet as a Raman reporter, exhibiting an enhancement factor of 2.7 × 107 and a relative standard deviation of 5.04%. Thiram of a lower concentration than the maximum residue limit on the cucumber surface could easily be detected in situ by the proposed substrate, demonstrating its great potential for in-situ food safety analysis.
Maximising D − T fusion power by optimising the plasma composition and beam choice in JET
Authors: Van Eester D , Lerche E , Huynh P , Johnson T , Yadikin D , Štancar Ž , Aleiferis S , Frigione D , Garzotti L , Lomas P , Lowry C , Maslov M 
Published: March 2022

Abstract
JET has a neutral beam injection as well as a radio frequency (RF) system for bringing plasmas to fusion-relevant temperatures. The former allows D as well as T birth energies of the order of 100–120 keV while the latter has the flexibility to heat a variety of populations by adjusting the antenna frequency. In this paper it is illustrated that—when the JET plasma is heated—the power harvested from D − T fusion reactions favours operating away from the 50–50 D − T balance and that exploiting pure D beams is more beneficial than combined D and T beams as well as pure T beams. Although beam heating dominates the overall behaviour in JET—as much more beam power than wave power can be coupled to the plasma—RF heating allows efficient heating of the very core.
Development and experiment evaluation of a compact inchworm piezoelectric actuator using three-jaw type clamping mechanism
Authors: Deng Jie , Zhang Shijing , Li Yiqing , Ma Xuefeng , Gao Xiang , Xie Hui , Liu Yingxiang 
Published: March 2022

Abstract
A compact inchworm piezoelectric actuator using three-jaw type clamping mechanism is developed in this study. Different from the previous inchworm piezoelectric actuators constructed with guiding structures, the proposed actuator can drive an output shaft to realize linear motion without other auxiliary structures based on the automatic centering and guidance functions of the designed three-jaw type clamping mechanism, and a compact structure is obtained. The configuration of the actuator is presented to describe the operating principle in detail. Then the structures of the clamping and actuating units are designed by the assistance of finite element simulations. A prototype is fabricated and a compact structure is achieved with outer diameter of 34 mm and length of 40 mm. The experiments are performed to investigate the characteristics, a maximum speed of 155.5 μm s−1 and a thrust force of 12.3 N are achieved. The experimental results confirm that the proposed inchworm actuator can achieve a compact structure by adopting the designed three-jaw type clamping mechanisms, it has great potential in integration with precision equipment, which is conductive to apply in the fields of biological manipulation robots and aerospace devices.
Multi-scale nonlinear stress analysis of Nb3Sn superconducting accelerator magnets
Authors: Sun Eric Qiuli 
Published: March 2022

Abstract
A multi-scale nonlinear procedure to analyze the stress in Nb3Sn superconducting accelerator magnets is presented to address one of the most challenging obstacles currently facing the successful development of high-field superconducting magnets—the issue of stress management. The study demonstrates that gasket materials (special nonlinear materials) are capable of modeling the complex nonlinear deformation behavior of insulation layers within the Nb3Sn coil block and that Hill materials (orthotropic materials utilizing the Hill yield criterion) are suitable to enable homogenization of the filamentary regions and the resin-impregnated Nb3Sn Rutherford cables. With the whole magnet under preload, cool-down, and Lorentz forces, the nonlinear behavior of the Nb3Sn coil was simulated, in three orthongonal axes, using the combined properties of the gasket materials (insulation layers) and Hill materials (resin-impreganted cable). The procedure makes very few assumptions with regard to material properties because it incorporates actual measured stress–strain curves in the analysis. The coil was simulated to the level of detail of the insulation layers and resin-impregnated cables. The computed compressive azimuthal stresses of the cables were used to assess stress-induced performance degradation. Through submodeling, the area-weighted average axial strains of the strands were computed and employed to evaluate the strain-induced performance degradation. The overall performance degradation of the Nb3Sn coil was thus obtained, and this information was subsequently used to guide the design of the overall magnet. Besides Nb3Sn magnets, this versatile procedure can also be employed in the design of LTS, HTS, and room temperature magnets or of any structures ultilizing composite materials; specifically, it can be used to manage the stress and strain of HTS fusion magnets.
Enhanced generation of angle correlated photon-pairs in nonlinear metasurfaces
Authors: Mazzanti Andrea , Parry Matthew , Poddubny Alexander N , Della Valle Giuseppe , Neshev Dragomir N , Sukhorukov Andrey A 
Published: March 2022

Abstract
We reveal that strongly enhanced generation of photon pairs with narrow frequency spectra and sharp angular correlations can be realised through spontaneous parametric down-conversion in metasurfaces. This is facilitated by creating meta-gratings through nano-structuring of nonlinear films of sub-wavelength thickness to support the extended bound state in the continuum resonances, associated with ultra-high Q-factors, at the biphoton wavelengths across a wide range of emission angles. Such spectral features of photons can be beneficial for various applications, including quantum imaging. Our modelling demonstrates a pronounced enhancement, compared to unpatterned films, of the total photon-pair generation rate normalized to the pump power reaching 1.75 kHz mW−1, which is robust with respect to the angular bandwidth of the pump, supporting the feasibility of future experimental realisations.
Effect of hydrostatic pressure on structural and opto-electronic properties for barium based oxide perovskite
Authors: Erum Nazia , Iqbal Muhammad Azhar , Ashraf Fareed 
Published: March 2022

Abstract
In this study, the effects of hydrostatic pressure ranges from 0 Gpa to 20 Gpa on detailed pressure induced computations of Barium Zirconate BaZrO3, including initial geometry optimization, energy minimization calculations, total energy values, lattice parameters, energy band gaps (Eg), optical and elastic constants are reported. All subjected computational results are collected by applying Local Density Approximation functional proposed by Ceperley-Alder and reformulated by Perdew-Zunger (LDA-CAPZ) using Cambridge Serial Total Energy Package (CASTEP) module under the formulation of Density Function Theory (DFT). The reduced nature of cell volume as well as lattice constants confirm the structural compressibility of BaZrO3 under the application of applied pressure. Increasing bulk modulus values indicate maximum structural stiffness of BaZrO3 under applied pressure. The collected values are compared with available theoretical and experimental parameters. The investigated band structures predict direct bandgap of BaZrO3, that increase under the influence of applied pressure which tend to increase all optoelectronic behavior. So, the current investigation signifies, that these calculations provide a baseline for new researchers to establish further pressure investigations and could be helpful for the uses of BaZrO3 in optoelectronic applications.
General properties of terminating bands in the A = 110 and A = 160 mass regions
Authors: Shayestefar Mohadese , Kardan Azam 
Published: March 2022

Abstract
Band termination in different mass regions exhibits some similar characteristics. High spin states in odd-A
107−113Sb (Z = 51) and 155−157Ho (Z = 67) isotopes in addition to the N = 58 and N = 88 isotones are investigated within the cranked Nilsson-Strutinsky (CNS) approach. Also, experimental and calculation results are compared with a focus on the number of the holes and particles in different orbitals. Consequently, we deduce similarities and differences in the structure of the terminating bands in A ∼ 110 and the A ∼ 160 mass regions.