bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of carbon dots on tuning molecular alignment, dielectric and electrical properties of a smectogenic cyanobiphenyl-based liquid crystal material
Authors: P Priscilla , Kumar Sandeep , Gathania Arvind K , Singh Ashwani Kumar , Supreet  , Prakash Jai , Kumar Sanjeev , Malik Praveen , Castagna Riccardo , Singh Gautam 
Published: May 2024

Abstract
Here, we demonstrate the effect of dispersing organosoluble carbon dots (CDs, ∼7–8 nm) on tuning the molecular alignment, dielectric and electrical properties of smectic A (SmA) and nematic (N) mesophases of a thermotropic smectogenic LC material, 4-octyl-4′-cyanobiphenyl (8CB) in a planar anchored indium tin oxide (ITO) sample cell using polarized optical microscopy and dielectric spectroscopic techniques. The cross-polarized optical textures clearly show that the doping of CDs (concentration ⩾0.25 wt%) in planar anchored 8CB liquid crtstal (LC) led to the changing of its alignment from planar to vertical. Interestingly, such an induced vertical alignment remains stable throughout the SmA and N phases of the 8CB LC material. Moreover, the magnitude of the real dielectric permittivity is found to increase with increasing concentration of CDs and exhibits vertical alignment values for composites (⩾0.25 wt%). The observance of short axis molecular relaxation for composites (⩾0.25 wt%) without the application of bias field confirms again the induced vertical alignment. The accumulation of CDs at the substrate surface and their interaction with the alignment and ITO layers can be attributed as an important factor for such induced vertical alignment. The electrical conductivity of 8CB is observed to increase significantly with the addition of CDs (i.e. an increment of up to two orders of magnitude in composites compared to pure 8CB) and attributed to the lowering of viscosity and change in molecular alignment. We certainly believe that such tunable molecular alignment throughout the SmA and N phases of thermotropic smectogenic LC material (8CB) by dopant CDs could pave the way for their applications in flexible displays, biosensors, electro-optical memory and other tunable photonic devices.
Single current control of magnetization in vertical high-aspect-ratio nanopillars on in-plane magnetization layers
Authors: Honda Syuta , Sonobe Yoshiaki 
Published: May 2024

Abstract
Ferromagnetic pillars standing on a substrate hold promise for use in recording segments of multibit nonvolatile memories. These pillars exhibit high thermal stability in their magnetization owing to the influence of shape and perpendicular magnetic anisotropies. Recent micromagnetic simulations have demonstrated the feasibility of magnetization control in these pillars. Such control was achieved through the spin-transfer torque induced by the current flowing within the pillar and the spin-orbit torque generated by the current flowing through the heavy-metal lead at the bottom of the pillars. However, the presence of two current paths complicates circuit design, posing challenges in device integration. To solve this problem, we propose a new structure wherein a pillar is placed on a thin film with in-plane magnetization. When current flows through this structure, a torque is applied to the magnetization of the pillar, similar to that of the three-terminal structure. Magnetization reversal and control in the proposed structure were demonstrated using micromagnetic simulations. Specifically, magnetization reversal was achieved in a 100 nm-long permalloy pillar, whereas the magnetization corresponding to a three-bit sequence was generated in a 250 nm-long permalloy pillar. We propose two methods to control the magnetization of multibit memory. One method uses two different current intensities, whereas the other uses constant and pulsed currents of identical intensity. Notably, in the proposed structure, magnetization was controlled using only a unidirectional current. In particular, magnetization can be controlled with a pulsed current using a single current strength. This advancement will simplify the circuitry required to control magnetic memory, bringing the realization of magnetic memory devices closer to reality.
Anisotropic optoelectronic properties of lead-free Cs3Bi2I9 single-crystal photodetectors
Authors: Liu Jingyi , Nie Wanggao , Yan Lairong , Hu Hao , Zhang Guoqiang , Lin Ping , Hu Haihua , Xu Lingbo , Wang Peng , Cui Can 
Published: May 2024

Abstract
Lead-free halide perovskites have attracted widespread research interest due to their excellent optoelectronic properties and environmental friendliness. As one of the bismuth iodide compounds, Cs3Bi2I9 perovskite has been extensively explored in the field of photovoltaic devices and radiation detectors due to their non-toxic lead-free components and excellent stability. In this work, we successfully grow large-sized Cs3Bi2I9 single crystals (SC) with (l00) and (00l) crystal exposure facets by inverse temperature crystallization method. Under 525 nm light illumination with the intensity 15 mW cm−2 and 7 V bias, the (l00) Cs3Bi2I9 SC shows 2 times higher photocurrent, 3.6 times higher responsivity, and 2.8 times higher detectivity than the (00l) Cs3Bi2I9 SC, respectively. Superior response time in the scale of millisecond is obtained in both (l00) and (00l) Cs3Bi2I9 SCs. Based on the first-principle calculation, the (l00) SC possesses a higher charge distribution density and a wider dispersion distribution than (00l) SC, suggesting that more electrons in the (l00) SC can be excited in a wider range. The tighter arrangement of Cs+ and [BiI6]− octahedra in the (l00) SC than (00l) SC leads to the anisotropic photoelectric performance in (l00) and (00l) Cs3Bi2I9 SCs. Our results provide a strategy for the oriental growth of Cs3Bi2I9 SCs and the design of anisotropic optoelectronic devices with excellent performance.
Properties of the ionization region in a magnetron plasma at gas-aggregation-source-relevant pressure regime explored using a global model
Authors: Denysenko I B , Kersten H , Vahl A 
Published: May 2024

Abstract
A global (volume averaged) model is developed for the ionization region (IR) of a gas aggregation source (GAS) plasma. The case of using argon gas and a copper target is considered. The model describes the densities of thermal and hot electrons, argon and copper ions, copper atoms and argon atoms in different excited states, the temperature of thermal electrons, the kinetic energies of the ions with which they bombard the target, the sheath width near the target cathode and the energy fluxes by different plasma species to a planar probe in the IR. Also, the fraction of input power is estimated which is dissipated to energize the thermal electrons in the IR. The gas discharge properties are analyzed for different pressures and discharge currents under conditions corresponding to the experimental conditions (Gauter et al 2018 J. Appl. Phys.
124 073301). The calculated pressure- and current-dependences for the GAS properties are used to explain the measured dependences for the deposition rate and the energy flux. It is found that the deposition rate increases with increasing discharge current because of the growth of currents of copper atoms and ions. With increasing pressure, the rate decreases due to drop of the densities of copper atoms and ions because of decreasing the kinetic energies of the ions with which they bombard the target. The model indicates that in the gas-aggregation-source relevant pressure regime, the energy flux by ions dominates over the energy fluxes of other plasma species.
Metastable grain boundaries: the roles of structural and chemical disorders in their energetics, non-equilibrium kinetic evolution, and mechanical behaviors
Authors: He Miao , Wang Yuchu , Fan Yue 
Published: May 2024

Abstract
Complex environments in advanced manufacturing usually involve ultrafast laser or ion irradiation which leads to rapid heating and cooling and drives grain boundaries (GBs) to non-equilibrium states, featuring distinct energetics and kinetic behaviors compared to conventional equilibrium or near-equilibrium GBs. In this topical review, we provide an overview of both recent experimental and computational studies on metastable GBs, i.e. their energetics, kinetic behaviors, and mechanical properties. In contrast to GBs at thermodynamic equilibrium, the inherent structure energy of metastable GBs exhibits a spectrum instead of single value for a particular misorientation, due to the existence of microstructural and chemical disorder. The potential energy landscape governs the energetic and kinetic behaviors of metastable GBs, including the ageing/rejuvenating mechanism and activation barrier distributions. The unique energetics and structural disorder of metastable GBs lead to unique mechanical properties and tunability of interface-rich nanocrystalline materials. We also discuss that, in addition to structural disorder, chemical complexity in multi-components alloys could also drive the GBs away from their ground states and, subsequently, significantly impact on the GBs-mediated deformation. And under some extreme conditions such as irradiation, structural disorders and chemical complexity may simultaneously present at interfaces, further enriching of metastability of GBs and their physical and mechanical behaviors. Finally, we discuss the machine learning techniques, which have been increasingly employed to predict and understand the complex behaviors of metastable GBs in recent years. We highlight the potential of data-driven approaches to revolutionize the study of disorder systems by efficiently extracting the relationship between structural features and material properties. We hope this topical review paper could shed light and stimulate the development of new GBs engineering strategies that allow more flexibility and tunability for the design of nano-structured materials.
Purely ionically bonded cation paving the way to ultralow thermal conductivity and large thermoelectric figure of merit in Ruddlesden–Popper perovskite Cs2SnI2Br2
Authors: Majumdar Arnab , Chowdhury Suman , Ahuja Rajeev 
Published: May 2024

Abstract
Lower dimensional materials have gained quite a bit of popularity in the last few decades. Perovskite materials have been studied extensively for their photovoltaic properties. But for large scale application of photovoltaic materials, the thermal properties need to be studied. In this work, using first principles calculations, we have studied the thermal conductivity and thermoelectric performance of quasi two-dimensional (2D) Ruddlesden–Popper phase of perovskite, Cs2SnI2Br2. The Cs atoms are found to be ionically bonded to the halogens leading to low elastic constants and hence give rise to weak bonding. The large anharmonicity in this material causes the lattice thermal conductivity to be ultralow having a value of 0.30 W·m−1·K−1 at 300 K and therefore the thermoelectric figure of merit has been found to be high with a maximum value of 2.08 at 600 K. This lead-free 2D perovskite can be the precursor to a wide variety of similar materials with ultralow thermal conductivity.
Josephson diode effect in junctions of superconductors with band asymmetric metals
Authors: Soori Abhiram 
Published: May 2024

Abstract
At interfaces connecting two superconductors (SCs) separated by a metallic layer, an electric current is induced when there is a disparity in the phases of the two superconductors. We elucidate this phenomenon based on the weights of the Andreev bound states associated with the states carrying currents in forward and reverse directions. Typically, current phase relation (CPR) in Josephson junctions is an odd function. When time reversal and inversion symmetries are broken at the junction, CPR ceases to be an odd function and the system may exhibit Josephson diode effect. This phenomenon has been studied in spin orbit coupled systems under an external Zeeman field wherein the magnetochiral anisotropy is responsible for the Josephson diode effect. Recently introduced the band asymmetric metal (BAM) model presents a novel avenue, featuring an asymmetric band structure. We investigate DC Josephson effect in SC-BAM-SC junctions and find that band asymmetry can lead to Josephson diode effect and anomalous Josephson effect. We explain the mechanism behind these effects based on interference of plane wave modes within the Bogoliubov de-Genne formalism. We calculate diode effect coefficient for different values of the parameters.
Electron–electron scattering limits thermal conductivity of metals under extremely high electron temperatures
Authors: Karna Pravin , Giri Ashutosh 
Published: May 2024

Abstract
We report on the thermal transport properties of noble metals (gold, silver and copper) under conditions of extremely high electron temperatures (that are on the order of the Fermi energy). We perform parameter-free density functional theory calculations of the electron temperature-dependent electron–phonon coupling, electronic heat capacities, and thermal conductivities to elucidate the strong role played by the excitation of the low lying d-bands on the transport properties of the noble metals. Our calculations show that, although the three metals have similar electronic band structures, the changes in their electron–phonon coupling at elevated electron temperatures are drastically different; while electron–phonon coupling decreases in gold, it increases in copper and, it remains relatively unperturbed for silver with increasing electron temperatures of up to ∼60 000 K (or 5 eV). We attribute this to the varying contributions from acoustic and longitudinal phonon modes to the electron–phonon coupling in the three metals. Although their electron–phonon coupling changes with electron temperature, the thermal conductivity trends with electron temperature are similar for all three metals. For instance, the thermal conductivities for all three metals reach their maximum values (on par with the room-temperature values of some of the most thermally conductive semiconductors) at electron temperatures of ∼6000 K, and thereafter monotonically decrease due to the enhanced effect of electron–electron scattering for electronic states that are further away from the Fermi energy. As such, only accounting for electron–phonon coupling and neglecting electron–electron scattering can lead to large over-predictions of the thermal conductivities at extremely high electron temperatures. Our results shed light on the microscopic understanding of the electronic scattering mechanisms and thermal transport in noble metals under conditions of extremely high electron temperatures and, as such, are significant for a plethora of applications such as in plasmonic devices that routinely leverage hot electron transport.
Interplay of lattice-spin-orbital coupling and Jahn–Teller effect in noncollinear spinel Ti
x
Mn1−x
(Fe
y
Co1−y
)2O4: a neutron diffraction study
Authors: Pramanik P , Singha A D , Reehuis M , Pittala S , Joshi D C , Sarkar T , Tovar M , Hoser A , Hoffmann J–U , Thota S 
Published: May 2024

Abstract
Local magnetostructural changes and dynamical spin fluctuations in doubly diluted spinel Ti
x
Mn1‒x
(Fe
y
Co1‒y
)2O4 has been reported by means of neutron diffraction and magnetization studies. Two distinct sets of compositions (i) x(Ti) = 0.20 and y(Fe) = 0.18; (ii) x(Ti) = 0.40 and y(Fe) = 0.435 have been considered for this study. The first compound of equivalent stoichiometry Ti0.20Mn0.80Fe0.36Co1.64O4 exhibits enhanced tetragonal distortion across the ferrimagnetic transition temperature T
C = 258 K in comparison to the end compound MnCo2O4 (T
C ∼ 180 K) with a characteristic ratio c
t/√2a
t of 0.99795(8) demonstrating robust lattice-spin-orbital coupling. However, in the second case Ti0.40Mn0.60Fe0.87Co1.13O4 with higher B-site compositions, the presence of Jahn–Teller ions with distinct behavior appears to counterbalance the strong tetragonal distortion thereby ceasing the lattice-spin-orbital coupling. Both the investigated systems show the coexistence of noncollinear antiferromagnetic and ferrimagnetic components in cubic and tetragonal settings. On the other hand, the dynamical ac-susceptibility, χ
ac(T) reveals a cluster spin-glass state with Gabay–Toulouse (GT) like mixed phases behaviour below T
C. Such dispersive behaviour appears to be sensitive to the level of octahedral substitution. Further, the field dependence of χ
ac(T) follows the weak anisotropic GT-line behaviour with crossover exponent Φ lies in the range 1.38–1.52 on the H–T plane which is in contrast to the B-site Ti substituted MnCo2O4 spinel that appears to follow irreversible non-mean-field AT-line behaviour (Φ ∼ 3 + δ). Finally, the Arrott plots analysis indicates the presence of a pseudo first-order like transition (T < 20 K) which is in consonance with and zero crossover of the magnetic entropy change within the frozen spin-glass regime.
Rapid measurement method for key dimensions of train wheelset based on improved image processing algorithm
Authors: Fang Yu , Wang Jingang , Zhu Zhongkui , Xiao Liming , Yuan Tianchen , Liu Xintian , Gao Weiwei 
Published: May 2024

Abstract
The key dimensions of train wheelsets change with the increase of running time. To ensure the safe operation of the train, the key dimensions should meet the relevant technical requirements. Maintenance of wheelsets and measurement of key dimensions are important part of the daily maintenance work. A rapid measurement method based on image processing algorithms for key dimensions of hand-held wheelsets integrating multiple parameter measurements is studied. The general framework of the system is examined and the roles of the modules are described. The optical center for the initial position of the continuous line spot is searched. The continuous line spot center extraction algorithm during tread measurement is optimized. A three-dimensional model is reconstructed using point cloud data, then key dimensions are measured and calculated from the model. In order to verify the feasibility of the method, traditional measurement methods are used for comparison tests. The results show that the method is effective in the daily maintenance of trains.
Surface defect detection and semantic segmentation with a novel lightweight deep neural network
Authors: Huang Qiang , Li Fudong , Yang Yuequan , Tao Xian , Li Wei , Wang Xu , Wang Yong 
Published: May 2024

Abstract
Current approaches to defect detection and segmentation make essential use of machine learning methods. To develop lightweight models is one of key tasks for many defect detection and segmentation applications. In this work, we present a lightweight trilateral parallel feature extraction with multi-feature aggregation network (TriMFANet) for surface defect detection and segmentation. In TriMFANet, the top lateral is the feature-rich extraction used to capture detailed information. The other two laterals, efficient semantic feature extraction (ESFE) and reverse ESFE, leverage Hadamard product attention to jointly extract deep-level global feature information. Additionally, the MFA module employs origin-symmetric sigmoid attention to enhance deep feature information and integrates the triple features. We conducted binary defect segmentation tasks on the SD-saliency-900 and RSDDs datasets, achieving outstanding performance in both S

α
and E

ξ
. For multi-class defect detection tasks on the NEU-Seg and MSD datasets, we rank first with mIoU scores of 79.0% and 81.2% respectively. Experimental results demonstrate that our lightweight model with only 90 K parameters exhibits excellent performance.
SLM-SLAM: a visual SLAM system based on segmented large-scale model in dynamic scenes and zero-shot conditions
Authors: Zhu Fan , Chen Ziyu , Jiang Chunmao , Xu Liwei , Zhang Shijin , Yu Biao , Zhu Hui 
Published: May 2024

Abstract
In practical applications, the existence of diverse dynamic objects can compromise the localization precision of most conventional Visual Simultaneous Localization and Mapping (VSLAM) systems. Simultaneously, many dynamic VSLAM systems based on neural networks require pre-training for specific application scenarios. We introduce SLM-SLAM, the first VSLAM system that implements zero-shot processing of dynamic scenes. It achieves the capability to handle various dynamic objects without the necessity for pre-training, enabling straightforward adaptation to different application scenarios. Firstly, we designed an open-world semantic segmentation module based on a segmented large-scale model to acquire semantic information in the scene. Subsequently, we devised a label-based strategy for selecting feature points, jointly optimizing poses with the weighted labels provided by both semantic and geometric information. Finally, we refined the keyframe selection strategy of ORB-SLAM3 to prevent matching errors caused by an insufficient number of remaining static feature points in the scene. We conducted experiments on the TUM dataset, the KITTI dataset, and real-world scenarios. The results indicate that in dynamic scenes, our SLM-SLAM significantly improves localization accuracy compared to ORB-SLAM3, and its performance is comparable to state-of-the-art dynamic VSLAM systems.
Utilizing integrated neutron diffraction and elastoplastic self-consistent crystal plasticity model to quantitatively assess the strengthening mechanism in Al–12.5Ce and Al–12.5Ce–0.4Mg alloys
Authors: Hu Xiaohua , Cheng Jiahao , Nawaz Kashif , Kesler Michael S , Chen Yan , An Ke 
Published: May 2024

Abstract
An integrated in-situ neutron diffraction and elastic plastic self-consistent crystal plasticity (EPSC-CP) modeling scheme is performed on a binary Al–12Ce alloy and a ternary Al–12Ce–0.4Mg alloys. Using this scheme, the constitutive parameters, i.e. elastic constants and slip system parameters of individual phases can be calibrated which can be used in microstructure-based CP models to predict materials performance. From this study, it is shown that the elastic constants of Al11Ce3 intermetallics calculated from density function theory calculation in the literature are rather accurate. When applied to the EPSC-CP model, the lattice strains of both the binary and ternary alloys are correctly predicted as compared with experiments, and large lattice strain differences between Al (100) plane and Al11Ce3 (010) plane are demonstrated. The slip system parameters calibrated by the scheme shows that the addition of 0.4 wt% Mg in the alloy has little influence on the critical resolved shear stress of initial dislocation glide in the Al matrix which caused plastic yield in the material. This can be explained by the very dilute Mg solute content in the Al solid solution, causing large spacing of Al–Mg lattice misfit sites and little impact on resistance of dislocation glide at initial yield. The 0.4 wt% Mg addition, on the other hand, has a large influence on the hardening term in the slip system parameters, indicating those Al–Mg misfit sites do help dislocation accumulation during the deformation. The impact of dilute Mg addition on the Al slip system parameters is also reflected in the flow behavior of the ternary alloy: little impact on the yield stress, but a large impact on working hardening and tensile strength of the materials which is consistent with the literature.