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arXiv 2023年

作者： Hussain, Naveed Ahmed, Shehzad Tep, Hüseyin U. Ullah, Kaleem Shahzad, Khurram Wu, Hui Shcherbakov, Maxim R. Department of Electrical Engineering and Computer Science University of California Irvine IrvineCA92697 United States State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing100084 China College of Physics and Optoelectronic Engineering Shenzhen University Guangdong518060 China Micro and Nano-Technology Program School of Natural and Applied Sciences Middle East Technical University Ankara06800 Turkey Department of Electrical and Computer Engineering University of Delaware NewarkDE19711 United States Department of Physics Middle East Technical University Ankara06800 Turkey

Mechanical straining-induced bandgap modulation in two-dimensional (2D) materials has been confined to volatile and narrow modulation due to substrate slippage and poor strain transfer. We report the thermomechanical modulation of the inherent bandgap in quasi-2D tellurium nanoflakes (TeNFs) via non-volatile strain induction during hot-press synthesis. We leveraged the coefficient of thermal expansion (CTE) mismatch between TeNFs and growth substrates by maintaining a high-pressure enforced non-slip condition during thermal relaxation (623 to 300K) to achieve the optimal biaxial compressive strain of -4.6 percent in TeNFs/sapphire. This resulted in an enormous bandgap modulation of 2.3 eV, at a rate of up to ~600 meV/%, which is two-fold larger than reported modulation rate. Strained TeNFs display robust band-to-band radiative excitonic blue photoemission with an intrinsic quantum efficiency (IQE) of c.a. 79.9%, making it promising for energy efficient blue LEDs and nanolasers. Computational studies reveal that biaxial compressive strain inhibits exciton-exciton annihilation by evading van-Hove singularities, hence promoting radiative-recombination. Bandgap modulation by such nonvolatile straining is scalable to other 2D semiconductors for on-demand nano(opto)-electronics. Copyright © 2023, The Authors. All rights reserved.

关键词： Energy gap

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Quasi periodic oscillations around Kerr-type black hole in the Starobinsky–Bel–Robinson theory of gravity

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physics of the Dark Universe 2024年 46卷

作者： Davlataliev, Akbar Narzilloev, Bakhtiyor Hussain, Ibrar Abdujabbarov, Ahmadjon Ahmedov, Bobomurat New Uzbekistan University Ulugh Beg Astronomical Institute Tashkent Institute of Irrigation and Agricultural Mechanization Engineers School of Electrical Engineering and Computer Science National University of Sciences and Technology Tashkent State Technical University Institute of Nuclear Physics Institute of Fundamental and Applied Research National Research University TIIAME

In this study of Kerr-type black hole within the Starobinsky–Bel–Robinson gravity, we unveil intriguing dynamics. We observe that the black hole spin weakens the effective potential, while the stringy parameter β of the Starobinsky–Bel–Robinson gravity, strengthens it, notably near the black hole. We further see that the deviations from the Kerr paradigm affect Innermost Stable Circular Orbit (ISCO) and Outermost Stable Circular Orbit (OSCO) regions. Moreover, the fundamental frequencies reveal the dominance of the β parameter near the black hole. Our analysis provides valuable insights into the possible black hole mass and β parameter for GRO J1655-40, XTE J1550-564, XTE J1859+226, GRS 1915+105 and H1743-322 under the Starobinsky–Bel–Robinson gravity, highlighting the role of quasi periodic oscillations behavior and black hole spin in defining these constraints. These findings have significant implications, highlighting the potential of the parameter β to rival or surpass the influence of the spin of the black hole, offering new insights into the behavior of black hole and spacetime beyond General Relativity. © 2024 Elsevier B.V.

关键词： QPOs Rotating black hole Starobinsky–Bel–Robinson gravity

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Topological superconductors from a materials perspective

arXiv

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arXiv 2023年

作者： Mandal, Manasi Drucker, Nathan C. Siriviboon, Phum Nguyen, Thanh Boonkird, Tiya Lamichhane, Tej Nath Okabe, Ryotaro Chotrattanapituk, Abhijatmedhi Li, Mingda Quantum Measurement Group MIT CambridgeMA02139 United States Department of Nuclear Science and Engineering MIT CambridgeMA02139 United States School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Department of Physics MIT CambridgeMA02139 United States Department of Chemistry MIT CambridgeMA02139 United States Department of Electrical Engineering and Computer Science MIT CambridgeMA02139 United States

Topological superconductors (TSCs) have garnered significant research and industry attention in the past two decades. By hosting Majorana bound states which can be used as qubits that are robust against local perturbations, TSCs offer a promising platform toward (non-universal) topological quantum computation. However, there has been a scarcity of TSC candidates, and the experimental signatures that identify a TSC are often elusive. In this perspective, after a short review of the TSC basics and theories, we provide an overview of the TSC materials candidates, including natural compounds and synthetic material systems. We further introduce various experimental techniques to probe TSC, focusing on how a system is identified as a TSC candidate, and why a conclusive answer is often challenging to draw. We conclude by calling for new experimental signatures and stronger computational support to accelerate the search for new TSC candidates. © 2023, CC BY.

关键词： Quantum computers

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Optical and plasmonic properties of high electron density epitaxial and oxidative controlled titanium nitride thin films

arXiv

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arXiv 2024年

作者： Chris-Okoro, Ikenna Cherono, Sheilah Akande, Wisdom Nalawade, Swapnil Liu, Mengxin Martin, Catalin Craciun, Valentin Kim, R. Soyoung Mahl, Johannes Cuk, Tanja Yano, Junko Crumlin, Ethan Schall, J. David Aravamudhan, Shyam Mihai, Maria Diana Zheng, Jiongzhi Zhang, Lei Hautier, Geoffroy Kumar, Dhananjay Department of Mechanical Engineering North Carolina A&T State University GreensboroNC27411 United States Joint School of Nanoscience and Nanoengineering North Carolina A &T State University GreensboroNC27401 United States School of Theoretical & Applied Sciences Ramapo College of New Jersey MahwahNJ07430 United States National Institute for Laser Plasma and Radiation Physics and Extreme Light Infrastructure for Nuclear Physics RO Magurele060042 Romania Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Chemistry University of Colorado BoulderCO80309 United States Horia Hulubei National Institute for Physics and Nuclear Engineering IF Măgurele077125 Romania Department of Physics National University of Science and Technology Politehnica RO Bucharest060042 Romania Department of Materials Science and Engineering Dartmouth College NH03755 United States

The present work is focused on designing and synthesizing negative-permittivity, high melting point, mechanically hard, and chemically stable thin film materials beyond commonly employed plasmonic noble metals. The materials studied here are titanium nitride (TiN) and its isostructural rocksalt oxide derivative, titanium oxynitrides (TiNO) in thin film geometry. The advantages of oxide derivatives of TiN are the continuation of similar free electron density as in TiN and the acquiring of additional features such as oxygen dependent semiconducting bandgaps and optical reflectivity values, opening a new dimension to semiconducting plasmonics research. This work reports a pulsed laser-assisted synthesis, detailed structural characterization and study of plasmonic properties of three sets of TiN/TiNO thin films with high electron density. The first two sets of TiN films were grown at 600°C and 700°C under a high vacuum condition (≤2 ×10-6Torr). The third set of TiN film was grown in the presence of 5 mTorr of molecular oxygen at 700 °C. The purpose of making these three sets of TiN/TiNO films was to understand the role of film crystallinity and the role of the oxygen content of TiN films on their optical and plasmonic properties. The results have shown that TiN films deposited in a high vacuum are metallic, have large optical reflectance, and have high optical and electrical conductivity. The TiN films, grown in 5 mTorr O2, were found to be partially oxidized and semiconducting with room temperature resistivity nearly three times larger than those of the TiN films grown under high vacuum conditions. The optical conductivity of these films was analyzed using a Kramers-Kronig transformation of reflectance and a Lorentz-Drude model;the optical conductivity determined by these two different methods agreed very well. To corroborate our experimental spectral observations, we have calculated the phonon dispersions and Raman active modes of TiNO using the virtual crystal approx

关键词： Plasmonics

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Vicinage effect on the yield of convoy electrons emitted from thin carbon foil induced by the penetration of 3.5-MeV/atom Cn+ ions

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Physical Review A 2024年第6期110卷 062826-062826页

作者： Y. Shiina R. Kinoshita S. Funada M. Matsuda M. Imai K. Kawatsura M. Sataka K. Sasa T. Kaneko Department of Physics Rikkyo University Tokyo 171-8501 Japan Graduate School of Pure and Applied Science University of Tsukuba 1-1-1 TennodaiTsukuba Ibaraki 305-8573 Japan Japan Atomic Energy Agency (JAEA) Tokai Ibaraki 319-1195 Japan Department of Nuclear Engineering Kyoto University Nishikyo Kyoto 615-8540 Japan School of Science and Technology Kyoto Institute of Technology Sakyo Kyoto 606-8585 Japan CRiES University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8577 Japan Institute of Pure and Applied Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan Department of Physics Okayama University of Science 1-1 Ridai-cho Kita-ku Okayama-shi Okayama 700-0005 Japan

We investigated the convoy electron yields resulting from bombardments of amorphous carbon foils with 3.5-MeV/atom Cn+ (n=1–3) cluster ions. The target thickness ranged from 3.0 to 29.7µg/cm2. A detailed analysis of the thickness dependence revealed that for bombardments with C2+ and C3+ ions, the convoy electron yield per atom, Yn/n, decreases with increasing target thickness and ultimately reaches an asymptotic value. The asymptotic value showed clear proportionality to the cluster size, n, indicating the presence of positive vicinity effects of Yn∝n2. We found that the escape length of the convoy electrons for C3+ and C2+ is much longer than that of the C+ bombardment. The present result suggests that the enhancement of the escape length could be the origin of this vicinage effect on the convoy electron yield.

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Validation of 3d Discrete Ordinate Transport Code with the Practical engineering Shielding Calculation Benchmark Problems

SSRN

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SSRN 2022年

作者： Yang, Chao Deng, Li Yu, Tao Fu, Yuanguang Li, Zhipeng Chen, Zhenping School of Nuclear Science and Technology University of South China Hengyang421200 China Research Center for Digital Nuclear Reactor Engineering and Technology of Hunan Province University of South China Hengyang421200 China Institute of Applied Physics and Computational Mathematics Beijing100094 China

This paper introduces extended validation works on JSNT-S code based on two practical engineering shielding calculation problems, the PWR Pressure Vessel Fluence Calculation Benchmark (PWR benchmark) and H. B. Robinson Unit 2 Pressure Vessel Benchmark (HBR-2 benchmark). The benchmarks put forward new challenges to the JSNT-S code, including the complexity of neutron source calculation, strong attenuation of the flux in the shielding material and modeling of complex shield structure geometry. SourceTrans code is developed to convert core pin-by-pin power distribution into neutron source distribution, visual modeling code JLAMT is used for 3D refined modeling of the benchmarks. Neutronic parameters provided in the benchmark report are validated, including the 47 group neutron flux spectrum, E>1MeV flux, E>0.1MeV flux, DAP rates, activation reaction rate and so on, the results show that JSNT-S code has good accuracy in simulating the practical engineering shielding calculation, and extend the reference solutions for benchmark problems. © 2022, The Authors. All rights reserved.

关键词： Benchmarking

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Fabrication and bioactivity studies of wollastonite/polycaprolactone composites

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International Journal of Nano and Biomaterials 2023年第2期10卷 86-99页

作者： Lakshmi, R. Choudhary, Rajan Senatov, Fedor Kaloshkin, Sergey Kothandam, Shobana Ponnamma, Deepalekshmi Sadasivuni, Kishor Kumar Swamiappan, Sasikumar Department of Chemistry Auxilium College Tamil Nadu Vellore632006 India Faculty of Materials Science and Applied Chemistry Rudolfs Cimdins Riga Biomaterials Innovations and Development Centre of RTU Institute of General Chemical Engineering Riga Technical University Pulka St 3 RigaLV-1007 Latvia Baltic Biomaterials Centre of Excellence Headquarters at Riga Technical University Kipsala Street 6A RigaLV-1048 Latvia National University of Science and Technology "MISiS" Moscow119049 Russia Department of Chemistry School of Advanced Sciences Vellore Institute of Technology Tamil Nadu Vellore632014 India Materials Science and Technology Program Department of Mathematics Statistics and Physics College of Arts and Sciences Qatar University P.O. Box 2713 Doha Qatar Center for Advanced Materials Qatar University P.O. Box 2713 Doha Qatar Department of Chemistry School of Advanced Sciences Vellore Institute of Technology Tamil Nadu Vellore632014 India

Current work investigates the influence of wollastonite on mechanical stability and biomineralisation ability of wollastonite/ polycaprolactone (PCL) composites (WP composites). The solvent casting particulate leaching method was used to prepare these composites. FT-IR spectra indicated the presence of functional groups associated with PCL and wollastonite. Scanning electron microscopy showed aggregated morphology and wollastonite particles were embedded in the PCL matrix. The incorporation of wollastonite leads to a more than three-fold increase in the compressive strength of the composites. Moreover, the composites containing 50% wollastonite exhibited better compressive strength than 80%. This observation suggested that if the concentration of a filler is exceeded beyond its critical concentration then the mechanical stability of the composite will be compromised. The composites revealed good apatite deposition ability. Thus, the biomineralisation ability and compressive strength of PCL can be improved by preparing its composites with bioceramics. © 2023 Inderscience Enterprises Ltd.

关键词： Bioceramics

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Characterizations of Second-order Nonlinear Optical Susceptibility for ϵ-phase Gallium Oxide

Characterizations of Second-order Nonlinear Optical Suscepti...

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2022 Compound Semiconductor Week, CSW 2022

作者： Zhou, Jingan Zhao, Xuan Xu, Rui Fu, Kai Li, Tao Xu, Mingfei He, Ziyi Robinson, Jacob T. Zhu, Hanyu Zhang, Xiaodong Zhao, Yuji Rice University Department of Electrical and Computer Engineering HoustonTX77005 United States Rice University Smalley-Curl Institute Applied Physics Graduate Program HoustonTX77005 United States Rice University Department of Materials Science and NanoEngineering HoustonTX77005 United States Arizona State University School of Electrical Computer and Energy Engineering TempeAZ85287 United States Suzhou Institute of Nano-tech and Nano-bionics CAS Key Laboratory of Nanodevices and Applications Suzhou215123 China

ISBN: (数字)9781665453400

ISBN: (纸本)9781665453400

In this work, we report the second-order nonlinear optical susceptibility χ(2) for epsilon phase Gallium Oxide (ϵ-Ga2O3) thin film on sapphire. ϵ-Ga2O3 exhibits hexagonal P63mc space group symmetry, which is a non-centrosymmetric structure with non-zero second order susceptibility. By focusing a pulsed laser beam on to a polished ϵ-Ga2O3 thin film, we collected the generated second harmonic photons with an ultra-sensitive femtowatt photodetector, obtaining effective second-order nonlinear optical susceptibility of χ(2) = 4.89×10-3 pm/V at wavelength of 800 nm. Two different measurement systems collecting reflected and transmitted photons were applied separately to make the result more convincing. The wavelength dependence from 790 nm to 900 nm and polarization dependence from TM mode to TE mode were measured as well. These results will be helpful for the design and fabrication of Ga2O3 based integrated photonics platform in the infrared-visible spectral range. © 2022 IEEE.

关键词： Gallium compounds

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Autonomous Electron Tomography Reconstruction with Machine Learning

arXiv

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arXiv 2023年

作者： Millsaps, William Schwartz, Jonathan Di, Zichao Wendy Jiang, Yi Hovden, Robert Department of Nuclear Engineering & Radiological Sciences University of Michigan Ann ArborMI United States Department of Materials Science and Engineering University of Michigan Ann ArborMI United States Mathematics and Computer Science Division Argonne National Laboratory LemontIL United States Advanced Photon Source Facility Argonne National Laboratory LemontIL United States Applied Physics Program University of Michigan Ann ArborMI United States

This manuscript is published in Microscopy and Microanalysis (DOI: 10.1093/micmic/ozad083). Modern electron tomography has progressed to higher resolution at lower doses by leveraging compressed sensing methods that minimize total variation (TV). However, these sparsity-emphasized reconstruction algorithms introduce tunable parameters that greatly influence the reconstruction quality. Here, Pareto front analysis shows that high-quality tomograms are reproducibly achieved when TV minimization is heavily weighted. However, in excess, compressed sensing tomography creates overly smoothed 3D reconstructions. Adding momentum to the gradient descent during reconstruction reduces the risk of over-smoothing and better ensures that compressed sensing is well behaved. For simulated data, the tedious process of tomography parameter selection is efficiently solved using Bayesian optimization with Gaussian processes. In combination, Bayesian optimization with momentum-based compressed sensing greatly reduces the required compute time-an 80% reduction was observed for the 3D reconstruction of SrTiO3 nanocubes. Automated parameter selection is necessary for large scale tomographic simulations that enable the 3D characterization of a wider range of inorganic and biological materials. © 2023, CC BY.

关键词： Compressed sensing

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Visualizing Field-free Deterministic Magnetic Switching of all–van der Waals Spin-Orbit Torque System Using Spin Ensembles in Hexagonal Boron Nitride

arXiv

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arXiv 2025年

作者： Zhang, Xi Zhou, Jingcheng Hu, Chaowei Deng, Kuangyin Wang, Chuangtang Agarwal, Nishkarsh Jin, Hanshang Al-Matouq, Faris A. Xu, Stelo Trivedi, Roshan S. Li, Senlei Rathi, Sumedh Lu, Hanyi Jiang, Zhigang Taufour, Valentin Hovden, Robert Zhao, Liuyan Cheng, Ran Xu, Xiaodong Chu, Jiun-Haw Du, Chunhui Rita Wang, Hailong School of Physics Georgia Institute of Technology AtlantaGA30332 United States Department of Physics University of Washington SeattleWA98105 United States Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Physics University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Physics and Astronomy University of California DavisCA95616 United States Department of Physics University of California San Diego La Jolla CA92093 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Physics and Astronomy University of California RiversideCA92521 United States Department of Materials Science and Engineering University of Washington SeattleWA98105 United States

Recently, optically active spin defects embedded in van der Waals (vdW) crystals have emerged as a transformative quantum sensing platform to explore cutting-edge materials science and quantum physics. Taking advantage of excellent solid-state integrability, this new class of spin defects can be arranged in controllable nanoscale proximity of target materials in vdW heterostructures, showing great promise for improving spatial resolution and field sensitivity of current sensing technologies. Building on this state-of-the-art measurement platform, here we report hexagonal boron nitride-based quantum imaging of field-free deterministic magnetic switching of room-temperature two-dimensional magnet Fe3GaTe2 in an all-vdW spin-orbit torque (SOT) system. By visualizing SOT-driven variations of nanoscale Fe3GaTe2 magnetic stray field profile under different conditions, we have revealed how the observed magnetic switching evolves from deterministic to indeterministic behavior due to the interplay between out-of-plane spins, in-plane spins and Joule heating. This understanding, which is otherwise difficult to access by conventional transport measurements, offers valuable insights on material design, testing, and evaluation of next-generation vdW spintronic devices. Copyright © 2025, The Authors. All rights reserved.

关键词： Van der Waals forces

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