bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tuning the semimetallic charge transport in the Weyl semimetal candidate Eu2Ir2O7 (111) epitaxial thin film with an all-in-all-out spin structure
Authors: Ghosh Mithun , Bhat Shwetha G , Pal Anand , Kumar P S Anil 
Published: February 2022

Abstract
We report the stoichiometric epitaxial growth of the Eu2Ir2O7 (111) thin film on YSZ substrate by a two-step solid phase epitaxy (SPE) method. An optimized post-annealing environment of the SPE was superior over the conventional air annealing procedure to get rid of the typical impurity phase, Eu2O3. The thickness-dependent structural study on Eu2Ir2O7 (111) thin films suggests a systematic control of Ir/Eu stoichiometry in our films, which is otherwise difficult to achieve. In addition, the low-temperature electrical resistivity studies strongly support the claim. The power-law dependence analysis of the resistivity data exhibits a power exponent of 0.52 in 50 nm sample suggesting possible disorder-driven semimetallic charge transport in the 3D Weyl semimetallic (WSM) candidate Eu2Ir2O7. In addition, the all-in-all-out/all-out-all-in antiferromagnetic domains of Ir4+ sublattice is verified using the field cooled magnetoresistance measurements at 2 K. Hall resistivity analysis indicate semimetallic hole carrier type dominance near the Fermi level up to the measured temperature range of 2–120 K. Altogether, our study reveals the ground state of stoichiometric Eu2Ir2O7 (111) thin film, with an indirect tuning of the off-stoichiometry using thickness of the samples, which is of interest in the search of the predicted 3D WSM phase.
Interface effects of Schottky devices built from MoS2 and high work function metals
Authors: Li Y D , Zhen W L , Weng S R , Hu H J , Niu R , Yue Z L , Xu F , Zhu W K , Zhang C J 
Published: February 2022

Abstract
Schottky junctions, formed by high work function metals and semiconductors, are important devices in electronics and optoelectronics. The metal deposition in traditional Schottky interfaces usually damages the semiconductor surface and causes defect states, which reduces the Schottky barrier height and device performance. This can be avoided in the atomically smooth interface formed by two-dimensional (2D) metals and semiconductors. For better interface tailoring engineering, it is particularly important to understand various interface effects in such 2D Schottky devices under critical or boundary conditions. Here we report the fabrication and testing of three types of MoS2 devices, i.e., using PtTe2, Cr and Au as contact materials. While the Cr/MoS2 contact is an ohmic contact, the other two are Schottky contacts. The van-der-Waals interface of PtTe2–MoS2 results in a well-defined OFF state and a significant rectification ratio of 104. This parameter, together with an ideality factor 2.1, outperforms the device based on evaporated Au. Moreover, a device in the intermediate condition is also presented. An abrupt increase in the reverse current is observed and understood based on the enhanced tunneling current. Our work manifests the essential role of doping concentration and provides another example for 2D Schottky interface design.
Anderson localization and multifractal spectrum at the transition point in a two-dimensional non-Hermitian AII† system
Authors: Yan Kun , Wang Yixian , Zhan Yuwei , Zhang Zhiyong , Wu Xinglong 
Published: February 2022

Abstract
The Anderson localization transition in a two-dimensional AII† system is studied by eigenvalue statistics and then confirmed by the multifractal analysis of the wave functions at the transition point. The system is modeled by a two-dimensional lattice structure with real-quaternion off-diagonal elements and complex on-site energies, whose real and imaginary parts are two independent random variables. Via finite-size scaling analysis of eigenvalue spacing ratios, we find the non-Hermiticity reduces the critical disorder and give an estimate of the critical exponent ν = 1.89, showing the system belongs to a new universal class other than the AII class and probably shares the same exponent with two-dimensional Hermitian DIII systems although they have different symmetries. The Anderson localization transition is further confirmed by checking the linearity in the parametric representation of the singularity strength and by checking the universality of the forms of the singularity spectra of different system sizes. The generalized dimensions are obtained as

D

1

=
1.80

and

D

2

=
1.62

.
Magnetic structures and electronic properties of cubic-pyrochlore ruthenates from first principles
Authors: Huebsch M-T , Nomura Y , Sakai S , Arita R 
Published: February 2022

Abstract
The magnetic ground states of R
2Ru2O7 and A
2Ru2O7 with R = Pr, Gd, Ho, and Er, as well as A = Ca, Cd are predicted devising a combination of the cluster-multipole (CMP) theory and spin-density-functional theory (SDFT). The strong electronic correlation effects are estimated by the constrained-random-phase approximation (cRPA) and taken into account within the dynamical-mean-field theory (DMFT). The target compounds feature d-orbital magnetism on Ru4+ and Ru5+ ions for R and A, respectively, as well as f-orbital magnetism on the R site, which leads to an intriguing interplay of magnetic interactions in a strongly correlated system. We find CMP + SDFT is capable of describing the magnetic ground states in these compounds. The cRPA captures a difference in the screening strength between R
2Ru2O7 and A
2Ru2O7 compounds, which leads to a qualitative and quantitative understanding of the electronic properties within DMFT.
A reinforcement transfer learning method based on a policy gradient for rolling bearing fault diagnosis
Authors: Wang Ruixin , Jiang Hongkai , Wu Zhenghong , Xu Jun , Zhang Jianjun 
Published: February 2022

Abstract
Accurate rolling bearing fault diagnosis is a basic guarantee of the safe operation of rotating machinery. Therefore, it is critical to select an appropriate fault diagnosis model. Selecting the optimal structure for intelligent fault diagnosis model has gradually become a research hot spot. At the same time, in practical engineering, sufficient data cannot always be guaranteed, which also increases the difficulty of accurate fault diagnosis. This paper proposes a reinforcement transfer learning method based on a policy gradient to identify the optimal structure of an intelligent fault diagnosis model when the number of training samples is insufficient. First, a policy gradient method is used to select the optimal child model in the source domain. Second, a transfer learning method is adopted to transfer the hyperparameters of the optimal child model from the source domain to the target domain. Finally, a small number of labeled training samples are used to fine-tune this model in the target domain. An adequate number of experiments proved the viability of proposed method, confirming the importance of the autonomous selection of a diagnostic model structure.
High-precision vapor pressure measurement apparatus with facile and inexpensive construction
Authors: Bhagwat Rohit , Sanadhya Sidharth , Gulotty Eva , Tucker Zachary , Ashfeld Brandon , Moghaddam Saeed 
Published: February 2022

Abstract
This study describes an apparatus for high-precision variable temperature measurement of liquid vapor pressure. The apparatus can be used to measure the vapor pressure using only 0.5 ml of the liquid sample. To evaluate the accuracy of the device measurement, water and 2-propanol are utilized as standard liquids, and their vapor pressure is measured with a maximum uncertainty of ∼1%. This apparatus can be replicated using inexpensive and commonly used laboratory fittings and fixtures, making it an indispensable tool for synthetic chemists and chemical engineers involved in the iterative synthesis of compounds, targeting different vapor–liquid equilibrium regimes.
Enhancement of the magnetic anisotropy in single semiconductor nanowires via surface doping and adatom deposition
Authors: Aras Mehmet , Güler-Kılıç Sümeyra , Kılıç Çetin 
Published: February 2022

Abstract
The magnetic anisotropy of single semiconductor (ZnO and GaN) nanowires incorporating both a transition metal (Co and Mn, respectively) as a substitutional surface dopant and a heavy metal (Au, Bi, or Pt) adatom is studied by performing density-functional supercell calculations with the Hubbard U correction. It is found that a substantial enhancement in the magnetic anisotropy energy is obtained through the deposition of Bi; the deposition of Au and Pt leads to significant variation in other magnetic properties, but not in the magnetic anisotropy energy. An analysis within a band description shows that the coexistence of Bi adatom and a surface dopant with large spin moment activates a mechanism involving reorientation and readjustment of the spin moments of electrons in occupied bands in response to the change of magnetization direction, which promotes giant magnetic anisotropy. Our results for adsorption energetics indicate that the accommodation of Bi in the neighborhood of the surface dopant is more likely in GaN nanowires, because the Bi adatom does (not) tend to be closer to the Mn (Co) dopant on the surface of GaN (ZnO) nanowire. The stability of GaN nanowire with giant magnetic anisotropy owing to the incorporation of both Mn and Bi is demonstrated by performing ab initio molecular dynamics simulations at temperatures considerably higher than room temperature. These results suggest that adatom deposition and surface doping can be used complementarily to develop single nanowire-based spintronic devices.
Versatile, rapid and robust nano-positioning of single-photon emitters by AFM-nanoxerography
Authors: Humbert M , Hallez Y , Larrey V , Fournel F , Palleau E , Paillard V , Cuche A , Ressier L 
Published: February 2022

Abstract
Atomic force microscopy (AFM) nanoxerography was successfully used to direct the assembly of colloidal nanodiamonds (NDs) containing nitrogen-vacancy (NV) centres on electrostatically patterned surfaces. This study reveals that the number of deposited NDs can be controlled by tuning the surface potentials of positively charged dots on a negatively charged background written by AFM in a thin PMMA electret film, yielding assemblies down to a unique single-photon emitter with very good selectivity. The mechanisms of the ND directed assembly are attested by numerical simulations. This robust deterministic nano-positioning of quantum emitters thus offers great opportunities for ultimate applications in nanophotonics for quantum technologies.
Impact of solid–liquid interfacial thermodynamics on phase-change memory RESET scaling
Authors: Lewis Matthew , Brush Lucien N 
Published: February 2022

Abstract
A model of the RESET melting process in conventional phase-change memory (PCM) devices is constructed in which the Gibbs–Thomson (GT) effect, representing local equilibrium at the solid–liquid interface, is included as an interfacial condition for the electro-thermal model of the PCM device. A comparison is made between the GT model and a commonly used model in which the interfacial temperature is fixed at the bulk melting temperature of the PCM material. The model is applied to conventional PCM designs in which a dome-shaped liquid/amorphous region is formed. Two families of solutions are computed representing steady state liquid regions, distinguished by their thermodynamic aspects. There is a family of solutions representing a hypothetical liquid nucleation process, and a family of larger steady-state liquid solutions representing the limit of the melting process. These ‘melting limits’ enable calculation of minima in voltage and corresponding current required for the RESET process. In this PCM configuration, the GT effect constrains the equilibrium solid–liquid interface temperature to remain above the bulk melting temperature during melting. The magnitude of this temperature difference increases with decreasing device size scale, thus requiring an increase in the required voltage and current needed for RESET compared to the case in which the interface temperature is approximated by the bulk melting temperature. This increase becomes substantial for active device dimensions in the <20 nm range. The impact of this phenomena on PCM device design is discussed.
Magneto-stimulation limits in medical imaging applications with rapid field dynamics
Authors: Grau-Ruiz Daniel , Rigla Juan P , Pallás Eduardo , Algarín José M , Borreguero José , Bosch Rubén , López-Comazzi Guillermo , Galve Fernando , Díaz-Caballero Elena , Gramage Carlos , González José M , Pellicer Rubén , Ríos Alfonso , Benlloch José M , Alonso Joseba 
Published: February 2022

Abstract

Objective. The goal of this work is to extend previous peripheral nerve stimulation (PNS) studies to scenarios relevant to magnetic particle imaging (MPI) and low-field magnetic resonance imaging (MRI), where field dynamics can evolve at kilo-hertz frequencies. Approach. We have constructed an apparatus for PNS threshold determination on a subject’s limb, capable of narrow and broad-band magnetic stimulation with pulse characteristic times down to 40 μs. Main result. From a first set of measurements on 51 volunteers, we conclude that the PNS dependence on pulse frequency/rise-time is compatible with traditional stimulation models where nervous responses are characterized by a rheobase and a chronaxie. Additionally, we have extended pulse length studies to these fast timescales and confirm thresholds increase significantly as trains transition from tens to a few pulses. We also look at the influence of field spatial distribution on PNS effects, and find that thresholds are higher in an approximately linearly inhomogeneous field (relevant to MRI) than in a rather homogeneous distribution (as in MPI). Significance. PNS constrains the clinical performance of MRI and MPI systems. Extensive magneto-stimulation studies have been carried out recently in the field of MPI, where typical operation frequencies range from single to tens of kilo-hertz. However, PNS literature is scarce for MRI in this fast regime, relevant to small (low inductance) dedicated MRI setups, and where the resonant character of MPI coils prevents studies of broad-band stimulation pulses. This work advances in this direction.
Impact of the electrode proximity on the streamer breakdown and development of pulsed dielectric barrier discharges
Authors: Wubs J R , Höft H , Kettlitz M , Becker M M , Weltmann K-D 
Published: February 2022

Abstract
The impact of the electrode proximity on the streamer breakdown and development of pulsed-driven dielectric barrier discharges (DBDs) in a single-filament arrangement has been investigated in a gas mixture of 0.1 vol% O2 in N2 at 0.6 bar and 1.0 bar. The gap distance was varied from 0.5 mm to 1.5 mm, and the applied voltage was adapted correspondingly to create comparable breakdown conditions in the gap. The development of the DBDs was recorded by an iCCD and a streak camera system, while fast electrical measurements provided insight into discharge characteristics such as the transferred charge and consumed energy. The results demonstrate that breakdown in a smaller gap is characterised by a slower streamer propagation but a significantly higher acceleration. It can therefore be concluded that the proximity of the cathode has a strong impact on the characteristics of the streamer breakdown. However, after the streamer has crossed the gap, the discharge structure in front of the anode was found to be the same independent of the actual gap distance.
High-dimensional data analytics in structural health monitoring and non-destructive evaluation: a review paper
Authors: Momeni Hamed , Ebrahimkhanlou Arvin 
Published: February 2022

AbstractThis paper aims to review high-dimensional data analytic (HDDA) methods for structural health monitoring (SHM) and non-destructive evaluation (NDE) applications. High-dimensional data is a type of data in which the number of features for each observation is much larger than the number of all observations. High-dimensional data may violate assumptions of the classic methods for statistical modeling and data analysis. Then, classic statistical modeling will no longer be applicable. HDDA methods were developed to overcome this challenge and analyze these types of data. In the field of SHM/NDE, there are several sources of high-dimensionality. Examples include a large number of data points in continuous waves/signals or high-resolution images/videos. HDDA methods are used as a dimension-reduction tool to preprocess data for further analysis, or they are directly implemented for damage detection and localization. This paper reviews six HDDA methods as well as existing and potential applications in SHM/NDE. Particularly, this paper discusses the vast range of implemented SHM/NDE applications from crack detection to missing data imputation. Furthermore, experimental and simulated datasets have been used to show the application of HDDA methods as hands-on examples. It is shown that the potential of HDDA for SHM/NDE studies is significantly more than the existing studies in the literature, and these methods can be used as a powerful tool that provides vast opportunities in SHM/NDE.
The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications
Authors: Huber Felix , Song Wenjuan , Zhang Min , Grilli Francesco 
Published: February 2022

Abstract
In recent years, the
T-A
formulation has emerged as an efficient approach for modelling the electromagnetic behaviour of high-temperature superconductor (HTS) tapes in the form of coated conductors (CCs). HTS CCs are characterized by an extremely large width-to-thickness ratio of the superconducting layer, normally up to 1000 ∼ 6000, which in general leads to a very large number of degrees of freedom. The
T-A
formulation considers the superconducting layer to be infinitely thin. The magnetic vector potential
A
is used to calculate the magnetic field distribution in all simulated domains. The current vector potential
T
is used to calculate the current density in the superconducting layer, which is a material simulated with a highly nonlinear power-law resistivity. This article presents a review of the
T-A
formulation. First, the governing equations are described in detail for different cases (2D and 3D, cartesian and cylindrical coordinates). Then, the literature on the implementation of
T-A
formulation for simulating applications ranging from simple tape assemblies to high field magnets is reviewed. Advantages and disadvantages of this approach are also discussed.
Protection of edge transport in quantum spin Hall samples: spin-symmetry based general approach and examples
Authors: Yevtushenko Oleg M , Yudson Vladimir I 
Published: February 2022

Abstract
Understanding possible mechanisms, which can lead to suppression of helical edge transport in quantum spin Hall (QSH) systems, attracted huge attention right after the first experiments revealing the fragility of the ballistic conductance. Despite the very intensive research and the abundance of theoretical models, the fully consistent explanation of the experimental results is still lacking. We systematize various theories of helical transport with the help of the spin conservation analysis which allows one to single out setups with the ballistic conductance being robustly protected regardless of the electron backscattering. First, we briefly review different theories of edge transport in the QSH samples with and without the spin axial symmetry of the electrons including those theoretical predictions which are not consistent with the spin conservation analysis and, thus, call for a deeper study. Next, we illustrate the general approach by a detailed study of representative examples. One of them addresses the helical edge coupled to an array of Heisenberg-interacting magnetic impurities (MIs) and demonstrates that the conductance remains ballistic even if the time-reversal symmetry on the edge is (locally) broken but the total spin is conserved. Another example focuses on the effects of the space-fluctuating spin–orbit interaction on the QSH edge. It reveals weakness of the protection in several cases, including, e.g. the presence of either the U(1)-symmetric, though not fully isotropic, MIs or generic electron–electron interactions.
Modeling of second-order nonlinear metasurfaces
Authors: Achouri Karim , Kiselev Andrei , Martin Olivier J F 
Published: February 2022

Abstract
We present a frequency-domain modeling technique for second-order nonlinear metasurfaces. The technique is derived from the generalized sheet transition conditions (GSTCs), which have been so far mostly used for modeling linear metasurfaces. In this work, we extend the GSTCs to include effective nonlinear polarizations. This allows retrieving the effective nonlinear susceptibilities of a given metasurface and predict its nonlinear scattering responses under arbitrary illumination conditions. We apply this modeling technique to the case of metasurfaces made of a periodic arrangement of T-shaped gold nanoparticles. For verification, several metasurfaces are fabricated and a fair agreement is found when comparing simulated data and experimental results. The proposed model may thus serve as a design platform to implement complex nonlinear metasurface based applications.
Weyl–Wigner description of massless Dirac plasmas: ab initio quantum plasmonics for monolayer graphene
Authors: Figueiredo José L , Bizarro João P S , Terças Hugo 
Published: February 2022

Abstract
We derive, from first principles and using the Weyl–Wigner formalism, a fully quantum kinetic model describing the dynamics in phase space of Dirac electrons in single-layer graphene. In the limit ℏ → 0, we recover the well-known semiclassical Boltzmann equation, widely used in graphene plasmonics. The polarizability function is calculated and, as a benchmark, we retrieve the result based on the random-phase approximation. By keeping all orders in ℏ, we use the newly derived kinetic equation to construct a fluid model for macroscopic variables written in the pseudospin space. As we show, the novel ℏ-dependent terms can be written as corrections to the average current and pressure tensor. Upon linearization of the fluid equations, we obtain a quantum correction to the plasmon dispersion relation, of order ℏ
2, akin to the Bohm term of quantum plasmas. In addition, the average variables provide a way to examine the value of the effective hydrodynamic mass of the carriers. For the latter, we find a relation in which Drude’s mass is multiplied by the square of a velocity-dependent, Lorentz-like factor, with the speed of light replaced by the Fermi velocity, a feature stemming from the quasi-relativistic nature of the Dirac fermions.
Reversible control of the metal-insulator transition in V2O3 thin films through plasma hydrogenation
Authors: Sultan M T , Arnalds U B 
Published: February 2022

Abstract
We investigate the effect of hydrogen plasma treatment on the metal-insulator transition (MIT) of epitaxial V2O3 films grown on c-Al2O3. The films were exposed to plasma at constant power for varying intervals. With increasing hydrogenation the films display a suppression of the MIT magnitude and temperature due to neutralization of structural defects and passivation of unpaired bonds by incorporation of atomic hydrogen as supported by relaxation in strain by XRD and Raman spectroscopy analysis, while stabilizing the metallic phase due to reduction in Peierls dimerization of V-V bonds. Heating to 350-400 °C the electrical characteristics of the film in the as-grown state are regained showing the possibility of reversibly controlling the MIT characteristics.