bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum spin Hall and quantum anomalous Hall states in magnetic Ti2Te2O single layer
Authors: Ma Hai-Yang , Guan Dandan , Wang Shiyong , Li Yaoyi , Liu Canhua , Zheng Hao , Jia Jin-Feng 
Published: February 2021

Abstract
Magnetic topological insulators, such as MnBi2Te4 have attracted great attention recently due to their application to the quantum anomalous Hall (QAH) effect. However, the magnetic quantum spin Hall (QSH) effect in two-dimensional (2D) materials has not yet been reported. Here based on first-principle calculations we find that Ti2Te2O, a van der Waals layered compound, can cherish both the QAH and QSH states, depending on the magnetic order in its single layer. If the single layer was in a chessboard antiferromagnetic (FM) state, it is a QSH insulator which carries two counterpropagating helical edge states. The spin–orbit-couplings induced bulk band gap can approach as large as 0.31 eV. On the other hand, if the monolayer becomes FM, exchange interactions would push one pair of bands away from the Fermi energy and leave only one chiral edge state remaining, which turns the compound into a Chern insulator (precisely, it is semimetallic with a topologically direct band gap). Both magnetic orders explicitly break the time reversal symmetry and split the energy bands of different spin orientations. To our knowledge, Ti2Te2O is the first compound that predicted to possess both intrinsic QSH and QAH effects. Our works provide new possibilities to reach a controllable phase transition between two topological nontrivial phases through magnetism tailoring.
Determination of the magnetic structures in orthoferrite CeFeO3 by neutron powder diffraction: first order spin reorientation and appearance of an ordered Ce-moment
Authors: Ritter Clemens , Ceretti Monica , Paulus Werner 
Published: February 2021

Abstract
High resolution and high intensity neutron powder diffraction are used to determine the temperature dependence of the crystallographic and magnetic structure of the orthoferrite CeFeO3. The high temperature G

x
-type magnetic coupling of the Fe-sublattice described by the Γ4 (G

x

A

y

F

z
) irreducible representation changes at the spin reorientation temperature T
SR = 228 K to a G

y
-type coupling of Γ1 (A

x

G

y

C

z
). The spin reorientation is of first order and sees a hysteresis of about 2.5 K at T
SR. Below 35 K faint magnetic peaks reflecting C

z
type magnetic coupling appear and are argued to be related to the Ce-sublattice. Magnetic moments at 2 K amount to μ
Fe = 4.15 μ
B and μ
Ce = 0.11 μ
B. CeFeO3 is only the second RFeO3 compound after DyFeO3 showing this ground state magnetic structure of the Fe-sublattice. The orthorhombic structure Pbnm is kept over the whole temperature range.
Quantum capacitance of coupled two-dimensional electron gases
Authors: Balasubramanian Krishna 
Published: February 2021

Abstract
Quantum capacitance effect is observed in nanostructured material stacks with quantum limited density of states. In contrast to conventional structures where two-dimensional electron gases (2DEG) with reduced density of states interact with a metal plate, here we explore the quantum capacitance effect in a unique structure formed by two 2DEG in a graphene sheet and AlGaN/GaN quantum well. The total capacitance of the structure depends non-linearly on the applied potential and the linear density of states in graphene leads to enhanced electric field leakage into the substrate causing a dramatic 50% drop in the overall capacitance at low bias potentials. We show theoretical projections of the quantum capacitance effect in the proposed device stack, fabricate the structure and provide experimental verification of the calculated values at various temperatures and applied potentials. The wide swing in the total capacitance is sensitive to the chemical potential of the graphene sheet and has multiple applications in molecular sensing, electro-optics, and fundamental investigations.
Valence tautomeric transition of bis(o-dioxolene) cobalt complex in solid state and solution
Authors: Guda A A , Chegerev M , Starikov A G , Vlasenko V G , Zolotukhin A A , Bubnov M P , Cherkasov V K , Shapovalov V V , Rusalev Yu V , Tereshchenko A A , Trigub A L , Chernyshev A V , Soldatov A V 
Published: February 2021

Abstract
Valence tautomer transition occurs mainly in 3d metalorganic complexes with redox-active ligands and makes them potential candidates for single-molecular switches. The transition occurs under temperature, pressure, or light-induced stimuli and is strongly affected by the intermolecular interactions. However single-crystal x-ray diffraction is not always applicable to such systems when crystal structure is destroyed upon transition or system is studied in the solution. Such an example is bis(o-semiquinonato) cobalt complex with TEMPO-functionalized iminopyridine ancillary ligand. In this work we apply two complementary techniques—ligand-sensitive Fourier transform infrared spectroscopy (FTIR) and metal sensitive Co K-edge x-ray absorption spectroscopy (XAS). In a solid state, a temperature hysteresis of magnetization larger than 40 K was observed upon cyclic cooling-heating. So, the temperature of phase transition upon cooling is about 40 K lower than that upon heating. In solution, the x-ray absorption spectra for high-temperature and low-temperature states were similar to that in the solid form, but the hysteresis was absent. Two methods are can probe valence tautomer transition, but XAS has an advantage for the liquid phase analysis and FTIR has larger sensitivity to the ligand related interactions in solid.
Evaluating humidity sensing response of graphene quantum dots synthesized by hydrothermal treatment of glucose
Authors: Khan Nouman , Nawaz Ahmad , Islam Bilal , Sayyad M Hassan , Joya Yasir Faheem , Islam Sara , Bibi Saira 
Published: February 2021

Abstract
Graphene quantum dots (GQDs) were prepared using a single-step hydrothermal treatment of glucose (C6H12O6) powder. X-ray diffraction patterns confirmed the random stacking or amorphous character of GQDs. Additionally, the UV-vis spectra confirmed the formation of GQDs with evident absorption peaks at 237 and 305 nm, which is attributed to π- π* and n- π* transitions correspondingly. The average size and surface roughness of graphene quantum dots were estimated by atomic force microscopy images and found to be 27.0 ± 1.0 and 2.3 nm, respectively. Afterwards, the effect of increasing relative humidity (RH) from 0%–95%, and frequency, was analyzed using the capacitive and resistive responses of synthesized GQDs. The capacitive output at 0.1 kHz revealed that initially capacitance remains constant (15.0 ± 1.0 pF) up to a humidity level ranging between 0%–50%. Likewise, capacitance also displayed stabilized behavior after frequency levels were increased i.e., 1.0 and 10 kHz, at a humidity ranging from 0%–55%. Moreover, capacitance showed a 115,455, 22,480 and 3,620% improvement from their stable values at each respective frequency level i.e., 0.1, 1.0 and 10 kHz. The capacitive sensitivity decreased to 84.20 and 96.83% at greater frequencies (1.0 and 10 kHz) in comparison to the sensitivity at 0.1 kHz facing similar variations in a humid environment. In contrast, resistance displayed an exponential decline by 99.9900, 99.9796 and 99.9925%, accordingly, when RH increases from 0 to 95% at 0.1, 1.0 and 10 kHz, respectively. However, with the rise in frequency level from 0.1 to 1.0 kHz, resistive sensitivity increased considerably to 69 and 158.5%, respectively, in two prominent humidity ranges i.e., 0 ≤ RH ≤ 25% and 25% ≤ RH ≤ 50%. A further increase in testing frequency to 10 kHz enhances the resistive sensitivity by 598.5 and 178.5% when compared with the lowest sensitivity values at two noticeable humidity levels, 0%–25% and 25%–50%. The response and recovery times of our specimen were better than most of previously fabricated GQDs and other carbon-derived nanomaterials, which makes the nano-GQDs of our study more suitable for RH sensor application.
Light-induced pyroelectric property of self-powered photodetectors based on all-inorganic perovskite quantum dots
Authors: Jin Lufan , Zhang Yating , Cao Mingxuan , Yu Yu , Chen Zhiliang , Li Yifan , Zhong Zhenggeng , Hua Xuebing , Xu Lingchao , Cai Chengyu , Hu Yongqi , Tong Xian , Yao Jianquan 
Published: February 2021

Abstract
All-inorganic cesium lead bromine (CsPbBr3) perovskites quantum dots (QDs) are one of the most photoelectric materials due to their high absorption coefficient, pronounced quantum-size effect, tunable optical property. Here, a self-powered PD based on all-inorganic CsPbBr3 perovskites QDs is fabricated and demonstrated. The light-induced pyroelectric effect is utilized to modulate the optoelectronic processes without the external power supply. The working mechanism of the PD is carefully investigated upon 532 nm laser illumination and the minimum recognizable response time of the self-powered PD is 1.5 μs, which are faster than those of most previously reported wurtzite nanostructure PDs. Meanwhile, the frequency and temperature independence of the self-powered PD are experimented and summarized. The self-powered PD with high performance is expected to have extensive applications in solar cell, energy harvesting, resistive random access memory.
Magnetoresistive micro-displacement sensor based on magnetorheological fluid
Authors: Li Xiaolin , Zhang Jiangtao , Shen Luyan , Qin Liming , Fu Qiang , Sun Youyi , Liu Yaqing 
Published: February 2021

Abstract
A novel magnetoresistance material based on magnetorheological fluid (MRF) was developed for applications in micro-displacement sensor. The MRF samples were fabricated by dispersing carbonyl iron particles (CIP) into a magnetic ion liquid (MIL) composed of 1-methylethyl ether-3-butylimidazole cation and [Fe2Cl7]− anions. The magnetoresistance characteristics were also systematically tested. It was found that the resistance value of MRF with a CIP content of 20 vol% decreased from 125 to 24.4 KΩ when increasing the magnetic field from 0 to 0.2 T. A sensor device was developed to study the displacement sensing characteristics of MRF, and found that the sensor had a high sensitivity of 0.1 Ω μm−1 and a high resolution of 10.0 μm. The excellent performance can be attributed to the low modulus and good stability of the MIL matrix, allowing for easy change of the resistance by controlling the magnetic field or displacement. In summary, these unique characters make the present MRF a promising magnetoresistance material with potential applications in displacement sensor.
Identification of multiple eigenmode growth rates towards real time detection in DIII-D and KSTAR tokamak plasmas
Authors: Liu T. , Wang Z.R. , Boyer M.D. , Munaretto S. , Wang Z.X. , Park B.-H. , Logan N.C. , Yang S.M. , Park J.-K. 
Published: February 2021

Abstract
The successful application of three-dimensional (3D) magnetohydrodynamic (MHD) spectroscopy enables us to identify the multi-mode eigenvalues in DIII-D and KSTAR tokamak experiments with stable plasmas. The temporal evolution of the multi-modes’ stabilities have been detected. The new method is numerically efficient allowing the real time detection of MHD modes’ stabilities during the discharge. The method performs active detection of the plasma stability by utilizing the upper and lower rows of internal non-axisymmetric coils to apply a wide variety of 3D fields. Multi-mode eigenvalues are extracted using subspace system identification of the plasma response measured by 3D-field magnetic sensors distributed at different poloidal locations. The equivalence of this new method with the one introduced by Wang (2019 Nucl. Fusion
59 024001) has been numerically corroborated. The more robust and efficient calculation developed here will enable real time monitoring of the plasma stability based on the extracted eigenvalues of stable modes.
A stable corridor for toroidal plasma compression
Authors: Brennan Dylan , Froese Aaron , Reynolds Meritt , Barsky Sandra , Wen Alex , Wang Zhirui , Delage Michael , Laberge Michel 
Published: February 2021

Abstract
A toroidal plasma compressed by a collapsing flux conserver is analyzed to reveal stable scenarios of operation to high compression ratios. The resistive and ideal MHD stability is calculated in full toroidal geometry, using the asymptotic matching method in realistic conditions, and comparing with nonlinear simulations. The near edge current profile, controlled by toroidal field ramping during compression, is shown to be critical to stability due to coupling between poloidal components of the least stable mode. The extension of a length of shaft on axis is also found to be critical at high compression, as the resulting good curvature region in magnetic field stabilizes pressure driven modes that would otherwise be unstable. This work extends from previous studies, which initially showed the existence of a stable scenario, to include findings of more extensive stable zones, detailed effects of geometry, and nonlinear simulations of the instabilities. The nonlinear simulations of the compression are consistent with the linear analyses, confirming both the conservation and stability properties.
Ion temperature gradient control using reinforcement learning technique
Authors: Wakatsuki T. , Suzuki T. , Oyama N. , Hayashi N. 
Published: February 2021

Abstract
Plasma with an internal transport barrier (ITB) is desirable for a steady-state tokamak reactor because of its high confinement quality and high bootstrap current fraction. However, the local pressure gradient tends to be steep and the plasma often becomes unstable. In this study, an ion temperature gradient control system based on neutral beam injection (NBI) is developed using the reinforcement learning technique. The response characteristics of an ion temperature gradient to NBI are non-linear and sensitive to experimental conditions, which makes it difficult to develop a robust control system. Our control system is trained for plasmas with a wide range of ITB strengths. Using the reinforcement learning technique, the system acquires a robust control feature through several thousand iterations of trial and error in an integrated transport simulation hosted by TOPICS. The control system is composed of neural networks (NNs) whose input variables are the ion temperature gradient, the current NBI power, and the NBI powers for several previous control time steps. The trained system can determine a control output which is suitable for the response characteristics inferred from the input variables. The trained control system is tested in the TOPICS simulation using plasma models based on two experimental plasmas of JT-60U with different ITB strengths. It is shown that the ion temperature gradient can be appropriately controlled for both plasmas, which supports the expectation that this system is applicable to real experiments.
The role of data variability and uncertainty in the probability of mitigating environmental impacts from cement and concrete
Authors: Miller Sabbie A 
Published: February 2021

Abstract
Concrete is the most produced manmade material globally. This widespread production results in significant anthropogenic environmental impacts, the awareness of which has spurred advances in material development to lower these burdens. However, proposed changes are often not assessed in the context of the data variability and uncertainty inherent in the environmental impact quantification methods employed. As such, the probability that any suggested strategy will result in a desired effect is not addressed. This work aims to quantitatively examine data variability, an inherent characteristic of elements in supply chains, and data uncertainty, a function of data quality for the system being modeled, in assessments of greenhouse gas (GHG) and air pollutant emissions from concrete production. Data variability is determined through ranges in requisite input values from the literature; data uncertainty is assessed through application of an established pedigree matrix method. Statistical analysis of the emissions from concrete production incorporating sources of variability and uncertainty are examined through Monte Carlo simulations. Concrete mixtures, representing a feasible structural concrete for use in California infrastructure and three alternative mixtures are assessed, as are three GHG emissions mitigation strategies, namely, a change in thermal energy fuel mix, a change in electricity grid, and use of carbon capture and storage. The distributions of emissions derived through statistical analyses are used to examine the probability of efficacy of these strategies, as well as potential co-benefits on air emissions. Results show each constituent change and each mitigation strategy considered would lead to a reduction in GHG emissions if only mean values are compared; however, the probability of these reductions varies. These findings suggest mitigation efforts may not be as definitive as current assessments suggest. Results indicate the importance of using statistical methods to target desirable mitigation efforts in the environmental impacts from concrete production.
Instantons for rare events in heavy-tailed distributions
Authors: Alqahtani Mnerh , Grafke Tobias 
Published: February 2021

Abstract
Large deviation theory and instanton calculus for stochastic systems are widely used to gain insight into the evolution and probability of rare events. At its core lies the fact that rare events are, under the right circumstances, dominated by their least unlikely realization. Their computation through a saddle-point approximation of the path integral for the corresponding stochastic field theory then reduces an inefficient stochastic sampling problem into a deterministic optimization problem: finding the path of smallest action, the instanton. In the presence of heavy tails, though, standard algorithms to compute the instanton critically fail to converge. The reason for this failure is the divergence of the scaled cumulant generating function (CGF) due to a non-convex large deviation rate function. We propose a solution to this problem by ‘convexifying’ the rate function through a nonlinear reparametrization of the observable, which allows us to compute instantons even in the presence of super-exponential or algebraic tail decay. The approach is generalizable to other situations where the existence of the CGF is required, such as exponential tilting in importance sampling for Monte-Carlo algorithms. We demonstrate the proposed formalism by applying it to rare events in several stochastic systems with heavy tails, including extreme power spikes in fiber optics induced by soliton formation.
Energy Efficiency in The Settlement Texture Through the Use of BIM
Authors: Aydin M A , Oral G K 
Published: February 2021

Abstract
In the emerging new and densely settled areas in Turkey, rapid construction and unplanned urbanization where energy efficiency approach is ignored, cause rapid destruction of natural environment and depletion of energy resources. In terms of economic and environmental aspects, the reduction of energy consumption is a matter of priority in the settlement texture design. The settlement texture is a significant design variable to control energy consumption. The dimensions of the buildings, their spacing (distance between buildings) and the arrangement of buildings with respect to one another are the design parameters which define the settlement texture. This study aims to determine the energy efficient settlement texture design parameters by the using Revit that software of BIM. In this context, the first step of the method of the study is to develop different settlement texture alternatives which benefit from the solar energy. In the second step, annual energy consumption for a selected residential building in the developed alternatives is calculated. Finally, calculated annual energy consumptions are analysed and the appropriate of the settlement texture design parameters in terms of energy efficiency are determined. As a result, this study is focused on determining the appropriate settlement texture in terms of energy efficiency by using BIM in order to take the right decisions in the design stage. According to the results of this limited studies with 48 different settlement textures, SF3-10-EW-0.5 achieved the lowest total energy consumption. However, in order to reach an acceptable general conclusion, similar studies should be analyzed for many alternatives.
Flexible indirect x-ray detector enabled by organic photodiode and CsPbBr3 perovskite quantum dot scintillator
Authors: Xiang Li , Wang Ya , Liu Xiyuan , Huang Xuekai , Xin Zhilong , Xu Yangbing , Liu Chuan , Wang Kai , Chen Jun , Yang Yang , Zhang Shengdong , Zhou Hang 
Published: February 2021

Abstract
X-ray photodetection are frequently used in medical diagnoses industrial inspection and environmental radiation detection. Currently, there is an ongoing effort to develop bendable or flexible x-ray photodetectors (PDs) to meet the demand on light weight and arbitrary shape detection system. Here, a highly bendable indirect x-ray PD is designed by coupling a P3HT:PC61BM organic photodetectors (OPDs) with a flexible perovskite quantum dots (QDs) embedded polymer scintillator. The flexible perovskite QDs scintillator exhibits high radioluminescence with emission peak centers at the 537 nm, which falls in maximum absorption range of poly(3-hexylthiophene) (P3HT). The OPD, with

2
μ

m

active layer, exhibits low dark currents in the range of tens of nanoampere per square centimeter over a wide reversed biased range. The OPD demonstrates detectable light signal down to

0

.1

μ

W

cm

−
2

and low dose detection capability. The coupling of perovskite QDs scintillator and OPD shows a sensitivity of 638 e nGy−1 mm−2

10

.2

μ

C G

y

−

1

c

m

−

2

at a dose rate of 1 mGy s−1, which brings the possibilities of realizing highly bendable x-ray PDs.
Pulsed laser deposition of oxide and metallic thin films by means of Nd:YAG laser source operating at its 1st harmonics: recent approaches and advances
Authors: Chaluvadi S K , Mondal D , Bigi C , Knez D , Rajak P , Ciancio R , Fujii J , Panaccione G , Vobornik I , Rossi G , Orgiani P 
Published: February 2021

Abstract
Quantum materials are central for the development of novel functional systems that are often based on interface specific phenomena. Fabricating controlled interfaces between quantum materials requires adopting a flexible growth technique capable to synthesize different materials within a single-run deposition process with high control of structure, stoichiometry, and termination. Among the various available thin film growth technologies, pulsed laser deposition (PLD) allows controlling the growth of diverse materials at the level of single atomic layers. In PLD the atomic species are supplied through an ablation process of a stoichiometric target either in form of polycrystalline powders or of a single crystal. No carrier gases are needed in the deposition process. The ablation process is compatible with a wide range of background pressure. We present results of thin-film growth by PLD obtained by using an Nd:YAG infrared pulsed laser source operating at its first harmonics. With respect to the traditional PLD systems—based on excimer KrF UV-lasers—optimal conditions for the growth of thin films and heterostructures are reached at large target-to-substrate distance. Merits and limitations of this approach for growing oxide and non-oxide thin films are discussed. The merits of an Nd:YAG laser to grow very high-quality thin films suggest the possibility of implementing compact in-situ setups e.g. integrated with analytical instrumentation under ultra-high vacuum conditions.