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Spin Seebeck effect at low temperatures in the nominally paramagnetic insulating state of vanadium dioxide

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arXiv 2022年

作者： Luo, Renjie Zhao, Xuanhan Chen, Liyang Legvold, Tanner J. Navarro, Henry Schuller, Ivan K. Natelson, Douglas Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Rice University HoustonTX77005 United States Department of Physics Center for Advanced Nanoscience University of California-San Diego La Jolla CA92093 United States Department of Electrical and Computer Engineering Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

The low temperature monoclinic, insulating phase of vanadium dioxide is ordinarily considered nonmagnetic, with dimerized vanadium atoms forming spin singlets, though paramagnetic response is seen at low temperatures. We find a nonlocal spin Seebeck signal in VO2 films that appears below 30 K and which increases with decreasing temperature. The spin Seebeck response has a non-hysteretic dependence on in-plane external magnetic field. This paramagnetic spin Seebeck response is discussed in terms of prior findings on paramagnetic spin Seebeck effects and expected magnetic excitations of the monoclinic ground state. Copyright © 2022, The Authors. All rights reserved.

关键词： Vanadium dioxide

Deep Potentials for Materials Science

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arXiv 2022年

作者： Wen, Tongqi Zhang, Linfeng Wang, Han Weinan, E. Srolovitz, David J. Department of Mechanical Engineering The University of Hong Kong Hong Kong DP Technology Beijing China AI for Science Institute Beijing China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing China HEDPS CAPT College of Engineering Peking University Beijing China School of Mathematical Sciences Peking University Beijing China Department of Mathematics and Program in Applied and Computational Mathematics Princeton University Princeton United States Shenzhen China

To fill the gap between accurate (and expensive) ab initio calculations and efficient atomistic simulations based on empirical interatomic potentials, a new class of descriptions of atomic interactions has emerged and been widely applied;i.e., machine learning potentials (MLPs). One recently developed type of MLP is the Deep Potential (DP) method. In this review, we provide an introduction to DP methods in computational materials science. The theory underlying the DP method is presented along with a step-by-step introduction to their development and use. We also review materials applications of DPs in a wide range of materials systems. The DP Library provides a platform for the development of DPs and a database of extant DPs. We discuss the accuracy and efficiency of DPs compared with ab initio methods and empirical potentials. Copyright © 2022, The Authors. All rights reserved.

关键词： Calculations

Hydrothermal Deposition of High Strength Biocompatible Magnesium Phosphate Coating Through in Situ Conversion of Az91d-3ca Magnesium Substrate

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SSRN

SSRN 2022年

作者： Iqbal, Farasat Ali, Asif Naveed, Mahnoor Ikram, Fakhera Fatima, Hira Interdisciplinary Research Centre in Biomedical Materials COMSATS University Islamabad Lahore Campus Pakistan Department of Applied Physics Faculty of Engineering and Architecture Ghent University Belgium Department of Chemistry COMSATS University Islamabad Lahore Campus Defence Road off Raiwind Road Lahore54000 Pakistan

Magnesium and its alloys are biodegradable and biocompatible with elastic modulus close to the natural bone which makes them suitable as an orthopedic implant. Poor corrosion resistance and high hydrogen evolution rate are two factors hindering their use as commercial implants. To overcome these challenges, a biocompatible magnesium phosphate coating was deposited using a single step hydrothermal method. Scanning Electron Microscopy (SEM/EDX) and X-Ray Diffraction (XRD) methods were used to analyze the structural and chemical compositions of these coatings. In addition, investigation on their adhesion, degradation, cellular proliferation, and gene expression were studied extensively. SEM analysis confirmed a uniform and defect-free deposition occurs in hydrothermal conditions. XRD validated the presence of Periclase (MgO), magnesium phosphate (Mg3(PO4)2) and Brucite (Mg (OH)2) phases. Degradation studies revealed the hydrogen evolution rate is remarkably decreased and corrosion properties were considerably improved as compared to the bare magnesium alloy. In-Vitro biocompatibility testing with pre-osteoblast (MC3T3-E1) via cell viability assay (Alamar blue reduction test) portrayed almost 100% host cell proliferation both in coated and positive control samples after 8 days. Comparing coated and untreated magnesium alloy in SEM images, greater cell adhesion was seen to the coated surface. It is concluded that magnesium phosphate coatings can be used commercially as they are compact, highly crystalline, defect-free, bioresorbable, cytocompatibility, well-adhered, and protective in nature. Hence, phosphate-coated magnesium alloy is qualified to be used to protect biodegradable metallic implants. © 2022, The Authors. All rights reserved.

关键词： Scanning electron microscopy

Simulation of environmental impacts on the synthesis of carbyne with more than 6000 atoms for emerging continuously tunable energy barriers in CNT-based transistors

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arXiv 2023年

作者： Wong, Chi Ho Yeung, Yan Ming Zhao, Xin Law, Wing Cheung Tang, Chak-Yin Mak, Chee Leung Leung, Chi Wah Shi, Lei Lortz, Rolf Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong Research Institute for Advanced Manufacturing The Hong Kong Polytechnic University Hong Kong Department of Physics The Hong Kong University of Science and Technology Hong Kong Department of Biomedical Engineering The Hong Kong Polytechnic University Hong Kong School of Science The Hong Kong University of Science and Technology Hong Kong Department of Applied Physics The Hong Kong Polytechnic University Hong Kong State Key Laboratory of Optoelectronic Materials and Technologies Nanotechnology Research Center School of Materials Science and Engineering Sun Yat-sen University Guangzhou510275 China

Transistors made up of carbon nanotubes CNT have demonstrated excellent current-voltage characteristics which outperform some high-grade silicon-based transistors. A continuously tunable energy barrier across semiconductor interfaces is desired to make the CNT-based transistors more robust. Despite the direct band gap of carbyne inside a CNT can be widely tuned by strain, the size of carbyne cannot be controlled easily. The production of a monoatomic chain with more than 6000 carbon atoms is an enormous technological challenge. To predict the optimal chain length of a carbyne in different molecular environments, we have developed a Monte Carlo model in which a finite-length carbyne with a size of 4000-15000 atoms is encapsulated by a CNT at finite temperatures. Our simulation shows that the stability of the carbyne@nanotube is strongly influenced by the nature and porosity of the CNT, the external pressure, the temperature and the chain length. We have observed an initiation of chain-breaking process in a compressed carbyne@nanotube. Our work provides much needed input for optimising the carbyne length to produce carbon chains much longer than 6000 atoms at ~300K. Design rules are proposed for synthesizing ~1% strained carbyne@(6,5)CNT as a component in CNT-based transistors to tune the energy barriers continuously. Copyright © 2023, The Authors. All rights reserved.

关键词： Atoms

Angle-resolved photoemission spectroscopy with an in situ tunable magnetic field

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arXiv 2023年

作者： Huang, Jianwei Yue, Ziqin Baydin, Andrey Zhu, Hanyu Nojiri, Hiroyuki Kono, Junichiro He, Yu Yi, Ming Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Smalley–Curl Institute Rice University HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Institute for Materials Research Tohoku University Katahira 2-1-1 Sendai980-8577 Japan Department of Applied Physics Yale University New HavenCT06511 United States

Angle-resolved photoemission spectroscopy (ARPES) is a powerful tool for probing the momentum-resolved single-particle spectral function of materials. Historically, in situ magnetic fields have been carefully avoided as they are detrimental to the control of photoelectron trajectory during the photoelectron detection process. However, magnetic field is an important experimental knob for both probing and tuning symmetry-breaking phases and electronic topology in quantum materials. In this paper, we introduce an easily implementable method for realizing an in situ tunable magnetic field at the sample position in an ARPES experiment and analyze magnetic field induced artifacts in ARPES data. Specifically, we identified and quantified three distinct extrinsic effects of a magnetic field: Constant energy contour rotation, emission angle contraction, and momentum broadening. We examined these effects in three prototypical quantum materials, i.e., a topological insulator (Bi2Se3), an iron-based superconductor (LiFeAs), and a cuprate superconductor (Pb-Bi2Sr2CuO6+x), and demonstrate the feasibility of ARPES measurements in the presence of a controllable magnetic field. Our studies lay the foundation for the future development of the technique and interpretation of ARPES measurements of field-tunable quantum phases. Copyright © 2023, The Authors. All rights reserved.

关键词： Photoelectrons

Room-temperature multiple ligands-tailored SnO_(2) quantum dots endow in situ dual-interface binding for upscaling efficient perovskite photovoltaics with high V_(OC)

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Light(Science & Applications) 2021年第12期10卷 2467-2481页

作者： Zhiwei Ren Kuan Liu Hanlin Hu Xuyun Guo Yajun Gao Patrick W.K.Fong Qiong Liang Hua Tang Jiaming Huang Hengkai Zhang Minchao Qin Li Cui Hrisheekesh Thachoth Chandran Dong Shen Ming-Fai Lo Annie Ng Charles Surya Minhua Shao Chun-Sing Lee Xinhui Lu Frédéric Laquai Ye Zhu Gang Li Department of Electronic and Information Engineering Research Institute for Smart Energy(RISE)Guangdong-Hong Kong-Macao(GHM)Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and DevicesThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Department of Electrical and Computer Engineering Nazarbayev UniversityNur-SultanKazakhstan The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China Hoffmann Institute of Advanced Materials Shenzhen Polytechnic7098 Liuxian BoulevardShenzhen 518055China Department of Applied Physics The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina King Abdullah University of Science and Technology(KAUST) KAUST Solar Center(KSC)Physical Sciences and Engineering Division(PSE)Material Science and Engineering Program(MSE)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Physics The Chinese University of Hong KongShatin 999077 Hong KongChina Center of Super-Diamond and Advanced Films(COSDAF) Department of ChemistryCity University of Hong KongHong KongChina

The benchmark tin oxide(SnO_(2))electron transporting layers(ETLs)have enabled remarkable progress in planar perovskite solar cell(PSCs).However,the energy loss is still a challenge due to the lack of“hidden interface”*** report a novel ligand-tailored ultrafine SnO_(2) quantum dots(QDs)via a facile rapid room temperature ***,the ligand-tailored SnO_(2) QDs ETL with multi-functional terminal groups in situ refines the buried interfaces with both the perovskite and transparent electrode via enhanced interface binding and perovskite *** novel ETLs induce synergistic effects of physical and chemical interfacial modulation and preferred perovskite crystallization-directing,delivering reduced interface defects,suppressed non-radiative recombination and elongated charge carrier *** conversion efficiency(PCE)of 23.02%(0.04 cm^(2))and 21.6%(0.98 cm^(2),V_(OC) loss:0.336 V)have been achieved for the blade-coated PSCs(1.54 eV E_(g))with our new ETLs,representing a record for SnO_(2) based blade-coated ***,a substantially enhanced PCE(V_(OC))from 20.4%(1.15 V)to 22.8%(1.24 V,90 mV higher V_(OC),0.04 cm^(2) device)in the blade-coated 1.61 eV PSCs system,via replacing the benchmark commercial colloidal SnO_(2) with our new ETLs.

关键词： perovskite interface quantum

FAST ABSOLUTE 3D CGO-BASED ELECTRICAL IMPEDANCE TOMOGRAPHY ON EXPERIMENTAL TANK DATA

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arXiv 2023年

作者： Hamilton, S.J. Muller, P.A. Isaacson, D. Kolehmainen, V. Newell, J. Shishvan, O. Rajabi Saulnier, G. Toivanen, J. The Department of Mathematical and Statistical Sciences Marquette University MilwaukeeWI53233 United States The Department of Mathematics Rensselaer Polytechnic Institute TroyNY12180 United States The Department of Applied Physics University of Eastern Finland KuopioFI-70210 Finland The Department of Mathematics & Statistics Villanova University VillanovaPA19085 United States The Department of Biomedical Engineering Rensselaer Polytechnic Institute TroyNY12180 United States The Department of Electrical and Computer Engineering University at Albany - SUNY AlbanyNY12222 United States

Objective: To present the first 3D CGO-based absolute EIT reconstructions from experimental tank data. Approach: CGO-based methods for absolute EIT imaging are compared to traditional TV regularized non-linear least squares reconstruction methods. Additional robustness testing is performed by considering incorrect modeling of domain shape. Main Results: The CGO-based methods are fast, and show strong robustness to incorrect domain modeling comparable to classic difference EIT imaging and fewer boundary artefacts than the TV regularized non-linear least squares reference reconstructions. Significance: This work is the first to demonstrate fully 3D CGO-based absolute EIT reconstruction on experimental data and also compares to TV-regularized absolute reconstruction. The speed (1-5 seconds) and quality of the reconstructions is encouraging for future work in absolute EIT. © 2023, CC BY.

关键词： Image reconstruction

Plasma Power Effect on Crystallinity and Density of Peald-Aln Thin Films： Toward Increasing Dielectric Constant and Breakdown Electric Field

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SSRN

SSRN 2023年

作者： Zhang, Xiao-Ying Peng, Duan-Chen Yan, Jia-Hao Zhang, Zhi-Xuan Ruan, Yu-Jiao Zuo, Juan Xie, An Wu, Wan-Yu Wuu, Dong-Sing Huang, Chien-Jung Lai, Feng-Min Lien, Shui-Yang Zhu, Wen-Zhang Xiamen Key Laboratory of Development and Application for Advanced Semiconduc tor Coating Technology School of Opto-electronic and Communication Engineering Xiamen University of Technology Xiamen361024 China National Measurement and Testing Center for Flat Panel Display Industry Xiamen Institute of Measurement and Testing Xiamen361024 China School of Materials Science and Engineering Xiamen University of Technology Xiamen361024 China Department of Materials Science and Engineering National United University Miaoli36063 Taiwan Department of Applied Materials and Optoelectronic Engineering National Chi Nan University Nantou54561 Taiwan Department of Applied Physics National University of Kaohsiung Kaohsiung University Rd. Kaohsiung81148 Taiwan Department of Biomedical Engineering Da-Yeh University Changhua51591 Taiwan

Aluminum nitride (AlN) film is a promising material which is used in various fields. In this study, AlN films with different plasma powers were grown by remote plasma atomic layer deposition. Saturation experiments have been applied in the plasma power between 1000 and 3000 W. The influence of plasma power on preferential orientation, chemical, optical, and electrical properties of AlN films are investigated. AlN films displayed multiphase hexagonal wurtzite crystal structure with (002) preferential orientation for higher plasma power, while the predominant orientation shifted toward (100) at lower plasma power. The optical emission spectroscopy analyses show that NH and NH2 radicals conduce to the deposition of AlN films and H radicals selectively dissociate Al-OH bonds which were on AlN film surface and etch deposition films. AFM measurements show that the 1500 W prepared AlN film with smallest surface roughness may be related to the relatively smaller concomitant crystal grains of (100) and (002). X-ray photoelectron spectroscopy investigation presents that oxygen content decreases as the plasma power increases. The obtained maximum value of dielectric constant and breakdown electrical field of AlN film deposited at 3000 W is 8.23 and 5.42 MV/cm, respectively. © 2023, The Authors. All rights reserved.

关键词： Aluminum nitride

Association of Antihypertensive Medication with Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Thickness

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Ophthalmology 2021年第3期128卷 393-400页

作者： Chong, Rachel S. Chee, Miao-Li Tham, Yih-Chung Majithia, Shivani Thakur, Sahil Teo, Zhen Ling Da Soh, Zhi Chua, Jacqueline Tan, Bingyao Wong, Damon W.K. Schmetterer, Leopold Sabanayagam, Charumathi Cheng, Ching-Yu Singapore National Eye Centre Singapore Singapore Eye Research Institute Singapore Ophthalmology & Visual Sciences Academic Clinical Program (Eye ACP) Duke-NUS Medical School Singapore Singapore SERI-NTU Advanced Ocular Engineering (STANCE) Singapore NTU Institute of Health Technologies Singapore School of Chemical and Biomedical Engineering Nanyang Technological University Singapore Department of Clinical Pharmacology Medical University of Vienna Vienna Austria Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria Institute of Molecular and Clinical Ophthalmology Basel Switzerland

Purpose: To evaluate the association between different classes of antihypertensive medication with retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) thickness in a nonglaucomatous multiethnic Asian population. Design: Population-based, cross-sectional study. Participants: A total of 9144 eyes for RNFL analysis (2668 Malays, 3554 Indians, and 2922 Chinese) and 8549 eyes for GC-IPL analysis (2460 Malays, 3230 Indians, and 2859 Chinese) aged 44 to 86 years. Methods: Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for collection of data on medication and other variables. Intraocular pressure (IOP) readings were obtained by Goldmann applanation tonometry before pupil dilation for fundoscopy and OCT imaging. Blood pressure (BP) was measured with an automatic BP monitor. Mean arterial pressure (MAP) was defined as diastolic BP plus 1/3 (systolic BP – diastolic BP). Regression models were used to investigate the association of antihypertensive medication with OCT measurements of RNFL and GC-IPL. Main Outcome Measures: Average and sectoral RNFL and GC-IPL thickness. Results: After adjusting for age, gender, ethnicity, MAP, IOP, body mass index (BMI), and presence of diabetes, we found that participants taking any type of antihypertensive medication (β = −0.83;95% confidence interval [CI], −1.46 to −0.02;P = 0.01), specifically angiotensin-converting enzyme inhibitors (ACEIs) (β = −1.66;95% CI, −2.57 to −0.75;P < 0.001) or diuretics (β = −1.38;95% CI, −2.59 to −0.17;P < 0.05), had thinner average RNFL in comparison with participants who were not receiving antihypertensive treatment. Use of a greater number of antihypertensive medications was significantly associated with thinner average RNFL (P for trend = 0.001). This association was most evident in the inferior RNFL quadrant in participants using ACEIs (β = −2.44;95% CI, −3.99 to −0.89;P = 0.002) or diuretics (β = −2.76;95% CI,

关键词： anti-hypertensive GC-IPL glaucoma hypertension medication OCT RNFL systemic medication