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Magnetism-induced second-order nonlinear optical responses in multiferroic BiFeO3

Physical Review B 2024年第1期110卷 014422-014422页

作者： Babu Baijnath Prasad Guan-Fu Liu Guang-Yu Guo Department of Physics and Center for Theoretical Physics Nano Science and Technology Program Taiwan International Graduate Program Physics Division

Nonlinear optical (NLO) responses of noncentrosymmetric nonmagnets have drawn a lot of attention in the past decades because of their significance in materials characterization, green energy, and device applications. On the other hand, magnetism not only can break the inversion symmetry in centrosymmetric crystals but also introduce additional NLO phenomena in noncentrosymmetric materials, thus enabling the magnetic field control of light-matter interactions. However, the magnetism-induced NLO responses have rarely been studied so far. In this paper, we study the magnetism-induced NLO responses of multiferroic bismuth ferrite (BiFeO3) based on density-functional-theory calculations. First, we find that the calculated magnetism-induced second-harmonic generation (SHG) susceptibilities are large and the SHG intensity is tunable with the reversal of magnetization. In particular, the interference between crystallographic SHG and magnetically induced SHG components results in a strong magnetic contrast of the SHG signal of ∼440% at SHG photon energy of 4.82 eV, thus enabling a magnetic control of the SHG in multiferroic BiFeO3. Also, because of the sensitivity of the SHG signal to the direction of the Néel vector, the SHG can be utilized to detect the reversal of the Néel vector in the AFM materials, which is an important issue for AFM spintronics. Second, the calculated bulk photovoltaic effects (BPVE) in BiFeO3 are also strong, being larger than some well-known NLO compounds such as BaTiO3, GaAs, CdS, and CdSe. Finally, we analyze the origins of the prominent features in the NLO response spectra in terms of the calculated quantum geometric quantities. Our interesting findings suggest that the magnetism-driven NLO responses in BiFeO3 are significant, anisotropic, and tunable and that understanding the magnetism-driven components of both SHG and BPVE is essential for their applications in, e.g., multiferroic-based photovoltaic devices and second-harmonic generation.

关键词： Antiferromagnetism Electronic structure Nonlinear optical susceptibility Photogalvanic effect Second order nonlinear optical processes Antiferromagnets Magnetic semiconductors Multiferroics Density functional theory First-principles calculations

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Chemical Evolution in the Green Synthesis of Micro and Nanoparticles of Calcium Oxide

SSRN

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SSRN 2023年

作者： Waldman, Walter Ruggeri dos Santos Araújo, Patrícia Mambrini, Giovanni Pimenta Graduate Program of Materials Science Federal University of São Carlos Campus Sorocaba Brazil Physics Chemistry and Mathematics Department Federal University of São Carlos Campus Sorocaba Brazil

Production of metal oxides is considered toxic, complex and environmentally unfriendly. We studied the use of polysaccharide-metal complexes as a synthesis greener alternative. We studied the influence of heating rates and salt concentrations during gelification and followed the chemical evolution as a function of the temperature from the raw material to the final product. Samples were collected at 200, 400, 600, 800, 1000, and 1100 °C and characterized by XRD, FTIR, and SEM to track crystalline domains, chemical groups, and morphology variation. Different production conditions presented different pathways toward the final product, mainly inthe steps up to 600 °C. We could assess the temperatures where it happens the polymer decomposition, the CaCO3 formation, the complete conversion of CaCO3 to CaO, and the formation of NaCl as an intrinsic contaminant. Additionally, we detect the influence of theproduction conditions on the reaction yield and the resistance against moisture absorption. © 2023, The Authors. All rights reserved.

关键词： Lime

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Slow and Stored Light via Electromagnetically Induced Transparency Using A Λ-type Superconducting Artificial Atom

arXiv

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arXiv 2024年

作者： Chu, Kai-I Lu, Xiao-Cheng Chiang, Kuan-Hsun Lin, Yen-Hsiang Chen, Chii-Dong Yu, Ite A. Liao, Wen-Te Chen, Yung-Fu Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taiwan Department of Physics National Central University Taoyuan City32001 Taiwan Department of Physics National Tsing Hua University Hsinchu30013 Taiwan Institute of Physics Academia Sinica Taipei11529 Taiwan Center for Quantum Science and Technology National Tsing Hua University Hsinchu30013 Taiwan Quantum Technology Center National Central University Taoyuan City32001 Taiwan Physics Division National Center for Theoretical Sciences Taipei10617 Taiwan

Recent progresses in Josephson-junction-based superconducting circuits have propelled quantum information processing forward. However, the lack of a metastable state in most superconducting artificial atoms hinders the development of photonic quantum memory in this platform. Here, we use a single superconducting qubit-resonator system to realize a desired Λ-type artificial atom, and to demonstrate slow light with a group velocity of 3.6 km/s and the microwave storage with a memory time extending to several hundred nanoseconds via electromagnetically induced transparency. Our results highlight the potential of achieving microwave quantum memory, promising substantial advancements in quantum information processing within superconducting circuits. Copyright © 2024, The Authors. All rights reserved.

关键词： Slow light

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Oxygen Vacancy Formation Energy in Metal Oxides: High Throughput Computational Studies and Machine Learning Predictions

arXiv

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arXiv 2023年

作者： Baldassarri, Bianca He, Jiangang Gopakumar, Abhijith Griesemer, Sean Salgado-Casanova, Adolfo J.A. Liu, Tzu-Chen Torrisi, Steven B. Wolverton, Chris Graduate Program in Applied Physics Northwestern University EvanstonIL United States Department of Materials Science Northwestern University EvanstonIL United States Toyota Research Institute United States

The oxygen vacancy formation energy (∆Evf) governs defect dynamics and is a useful metric to perform materials selection for a variety of applications. However, density functional theory (DFT) calculations of ∆Evf come at a greater computational cost than the typical bulk calculations available in materials databases due to the involvement of multiple vacancy-containing supercells. As a result, available repositories of direct calculations of ∆Evf remain relatively scarce, and the development of machine learning models capable of delivering accurate predictions is of interest. In the present, work we address both such points. We first report the results of new high-throughput DFT calculations of oxygen vacancy formation energies of the different unique oxygen sites in over 1000 different oxide materials, which together form the largest dataset of directly computed oxygen vacancy formation energies to date, to our knowledge. We then utilize the resulting dataset of ∼2500 ∆Evf values to train random forest models with different sets of features, examining both novel features introduced in this work and ones previously employed in the literature. We demonstrate the benefits of including features that contain information specific to the vacancy site and account for both cation identity and oxidation state, and achieve a mean absolute error upon prediction of ∼0.3 eV/O, which is comparable to the accuracy observed upon comparison of DFT computations of oxygen vacancy formation energy and experimental results. Finally, we demonstrate the predictive power of the developed models in the search for new compounds for solar-thermochemical water-splitting applications, finding over 250 new AA′BB′O6 double perovskite candidates. Copyright © 2023, The Authors. All rights reserved.

关键词： Forecasting

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Low-Crosstalk in 2D Waveguide Crossings by Metaheuristic Optimization Methods

Low-Crosstalk in 2D Waveguide Crossings by Metaheuristic Opt...

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Optics and Photonics Conference (SBFoton IOPC), SBFoton International

作者： Luana da França Vieira C. E. Rubio-Mercedes Vitaly Felix Rodriguez Esquerre Department of Computer Science Federal University of Western Bahia Barreiras Brazil Physics Engineering Program State University of Mato Grosso do Sul Dourados Brazil Graduate School of Electrical Engineering Federal University of Bahia Salvador Brazil

ISBN: (数字)9798350388176

ISBN: (纸本)9798350388183

This work describes the investigation of planar waveguide crossings using metaheuristic methods associated with the two-dimensional finite element method (2D-FEM). An optimization and measurement process are performed on the power transmission and crosstalk of the waveguide crossings and then the values calculated are compared with other studies in the literature. The best performing adjusted crossing is optimally designed by applying the following metaheuristics: Particle Swarm Optimization (PSO), Grey Wolf Optimizer (GWO), and a hybrid algorithm combining the Greedy Randomized Adaptive Search Procedure and Simulated Annealing (GRASP-SA). Transmission efficiency results higher than 97% and crosstalk below the -50 dB over a wide wavelength range, with a footprint of $\mathbf{4.9}\times \mathbf{4.9}\ \boldsymbol{\mu} \mathbf{m}^{\mathbf{2}}$ .

关键词： Performance evaluation Power measurement Metaheuristics Crosstalk Power transmission Simulated annealing Silicon Planar waveguides Optical waveguides Photonics

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Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 24

Partial observation can induce mechanistic mismatches in dat...

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Proceedings of the 38th International Conference on Neural Information Processing Systems

作者： William Qian Jacob A. Zavatone-Veth Benjamin S. Ruben Cengiz Pehlevan Biophysics Graduate Program and Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University Cambridge MA John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University and Department of Physics Harvard University Cambridge MA Biophysics Graduate Program Harvard University Cambridge MA Kempner Institute for the Study of Natural and Artificial Intelligence and John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University Cambridge MA

ISBN: (纸本)9798331314385

One of the central goals of neuroscience is to gain a mechanistic understanding of how the dynamics of neural circuits give rise to their observed function. A popular approach towards this end is to train recurrent neural networks (RNNs) to reproduce experimental recordings of neural activity. These trained RNNs are then treated as surrogate models of biological neural circuits, whose properties can be dissected via dynamical systems analysis. How reliable are the mechanistic insights derived from this procedure? While recent advances in population-level recording technologies have allowed simultaneous recording of up to tens of thousands of neurons, this represents only a tiny fraction of most cortical circuits. Here we show that observing only a subset of neurons in a circuit can create mechanistic mismatches between a simulated teacher network and a data-constrained student, even when the two networks have matching single-unit dynamics. In particular, partial observation of models of low-dimensional cortical dynamics based on functionally feedforward or low-rank connectivity can lead to surrogate models with spurious attractor structure. Our results illustrate the challenges inherent in accurately uncovering neural mechanisms from single-trial data, and suggest the need for new methods of validating data-constrained models for neural dynamics.

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Nonlinearity-Induced Nonreciprocity in Passive Silicon Gratings Supporting Quasi-Bound States in the Continuum

Nonlinearity-Induced Nonreciprocity in Passive Silicon Grati...

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CLEO: QELS_Fundamental science, QELS 2022

作者： Cotrufo, Michele Cordaro, Andrea Polman, Albert Alù, Andrea Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Van der Waals-Zeeman Institute Institute of Physics University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Center for Nanophotonics AMOLF Science Park 104 Amsterdam1098 XG Netherlands Physics Program Graduate Center of the City University of New York New YorkNY10016 United States

ISBN: (纸本)9781557528209

Optical nonlinearities, combined with structural asymmetry, can break reciprocity and realize devices that transmit light asymmetrically. We show the first experimental implementation of this concept for free-space radiation, using silicon metasurfaces supporting asymmetric quasi-bound states. © Optica Publishing Group 2022, © 2022 The Author(s)

关键词： Silicon

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Statistical biases in parameterized searches for gravitational-wave polarizations

arXiv

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arXiv 2025年

作者： Imafuku, Hayato Takeda, Hiroki Nishizawa, Atsushi Watarai, Daiki Cannon, Kipp Graduate School of Science The University of Tokyo Tokyo113-0033 Japan Graduate School of Science The University of Tokyo Tokyo113-0033 Japan The Hakubi Center for Advanced Research Kyoto University Yoshida Ushinomiyacho Sakyo-ku Kyoto606-8501 Japan Department of Physics Kyoto University Kyoto606-8502 Japan Physis Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan Astrophysical Science Center Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan

In tests of gravity using gravitational waves (GWs), GW events analyzed are often selected based on specific criteria, particularly the signal-to-noise ratio (SNR). However, such event selection can introduce bias into parameter estimation unless the selection effect is appropriately taken into account in the analysis. In this paper, we investigate how event selection with certain prior information affects parameter inference within the scalar-tensor polarization framework, focusing on the measurement of the scalar mode amplitude parameters. We find that for the Tensor+Scalar(dipole) model, the amplitude of the scalar dipole radiation is overestimated when its true value is nonzero while there is no false deviation in the absence of the scalar mode. The same bias is expected to occur also for the Tensor+Scalar(quadrupole) model. However, error typically exceeds the bias as the scalar quadrupole mode is difficult to be distinguished from the tensor mode. © 2025, CC BY.

关键词： Signal to noise ratio

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Brain activity of problem solving proccess: A systematic literarure review 7

Brain activity of problem solving proccess: A systematic lit...

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7th International Conference on Mathematics, science, and Education 2020, ICMSE 2020

作者： Juliyanto, E. Marwoto, P. Iswari, R.S. Wiyanto Nugroho, S.E. Mindyarto, B.N. Doctoral Program of Science Education Post Graduate Program Universitas Negeri Semarang Indonesia Science Education Departement Faculty of Teacher Training and Education Universitas Tidar Indonesia Departement of Physics Faculty of Mathematics and Natural Science Universitas Negeri Semarang Indonesia Departement of Biology Faculty of Mathematics and Natural Science Universitas Negeri Semarang Indonesia

Comprehending the problem-solving process is an effort that is no less important than teaching problem-solving skills at school. By understanding the problem-solving process, it will be easier to teach at school. Several neurological studies discuss activities in solving problems, but the scope of the discussion is narrow and in-depth. On the other hand, it requires complete information about how the problem-solving process is a complex cognitive process. This research is a systematic literature review using the PRISMA approach. The result shows that the problem-solving skills were developing based on ages of development. The effectiveness of problem-solving skills is characterized by minimal brain activity but produces the right solution. In addition, the result of the review shows that semantic ability and mathematical logic ability play an important role in a problem solving process. Getting complete problem solving process needs many parts of the brain. DLPFC and IFG are the dominant parts of the brain in the process of solving problems. © Published under licence by IOP Publishing Ltd.

关键词： Brain

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Temporal Mode Conversion in a Waveguide by Fast Motion of its Plates

Temporal Mode Conversion in a Waveguide by Fast Motion of it...

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CLEO: Fundamental science, CLEO:FS 2024 - Part of Conference on Lasers and Electro-Optics, CLEO 2024

作者： Solís, Diego M. Yin, Shixiong Galiffi, Emanuele Alù, Andrea Engheta, Nader Departamento de Tecnología de los Computadores y de las Comunicaciones University of Extremadura Cáceres10003 Spain City University of New York Photonics Initiative Advanced Science Research Center New York10031 United States City University of New York Physics Program Graduate Center New York10031 United States Department of Electrical and Systems Engineering University of Pennsylvania PhiladelphiaPA19104 United States

ISBN: (纸本)9781957171395

We show, semi-analytically and numerically, how the relativistic accelerated motion of a waveguide's parallel plates induces fast mode conversion including reflection, similar to the temporal interface by sudden variation of interplate distance through conductivity switching. © Optica Publishing Group 2024 © 2024 The Author(s)

关键词： Waveguides

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