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Chiral exceptional point enhanced active tuning and nonreciprocity in micro-resonators

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arXiv 2024年

作者： Lee, Hwaseob Chang, Lorry Kecebas, Ali Mao, Dun Xiao, Yahui Li, Tiantian Alù, Andrea Özdemir, Sahin K. Gu, Tingyi Department of Electrical and Computer Engineering University of Delaware NewarkDE19716 United States Department of Engineering Science and Mechanics Pennsylvania State University University ParkPA16802 United States Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States Department of Electrical and Computer Engineering Saint Louis University Saint LouisMO63103 United States

Exceptional points (EPs) have been extensively explored in mechanical, acoustic, plasmonic, and photonic systems. However, little is known about the role of EPs in tailoring the dynamic tunability of optical devices. A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity. A recently demonstrated route to chiral EPs via lithographically defined symmetric Mie scatterers on the rim of resonators has not only provided the much-needed mechanical stability for studying chiral EPs, but also helped reduce losses originating from nanofabrication imperfections, facilitating the insitu study of chiral EPs and their contribution to the dynamics and tunability of resonators. Here, we use asymmetric Mie scatterers to break the rotational symmetry of a microresonator, to demonstrate deterministic thermal tuning across a chiral EP, and to demonstrate EP-mediated chiral optical nonlinear response and efficient electro-optic tuning. Our results indicate asymmetric electro-optic modulation with up to 17dB contrast at GHz and CMOS-compatible voltage levels. Such wafer-scale nano-manufacturing of chiral electro-optic modulators and the chiral EP-tailored tunning may facilitate new micro-resonator functionalities in quantum information processing, electromagnetic wave control, and optical interconnects. © 2024, CC BY.

关键词： Microresonators

Large Negative Magnetoresistance in Antiferromagnetic Gd2Se3

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arXiv 2025年

作者： Chhetri, Santosh Karki Acharya, Gokul Graf, David Basnet, Rabindra Rahman, Sumaya Sharma, M.M. Upreti, Dinesh Nabi, Md. Rafique Un Kryvyi, Serhii Sakon, Josh Mortazavi, Mansour Da, Bo Churchill, Hugh Hu, Jin Department of Physics University of Arkansas FayettevilleAR72701 United States National High Magnetic Field Lab TallahasseeFL32310 United States Department of Chemistry & Physics University of Arkansas at Pine Bluff Pine BluffAR71603 United States Material Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States Department of Chemistry & Biochemistry University of Arkansas FayettevilleAR72701 United States MonArk NSF Quantum Foundry University of Arkansas FayettevilleAR United States Center for Basic Research on Materials National Institute for Materials Science Ibaraki Tsukuba305-0044 Japan

Rare earth chalcogenides provide a great platform to study exotic quantum phenomena such as superconductivity and charge density waves. Among various interesting properties, the coupling between magnetism and electronic transport has attracted significant attention. Here, we report the investigation of such coupling in α-Gd2Se3 single crystals through magnetic, calorimetric, and transport property measurements. α-Gd2Se3 is found to display an antiferromagnetic ground state below 11 K with metamagnetic spin-flop transitions. The magnetic fluctuations remain strong above the transition temperature. Transport measurements reveal an overall metallic transport behavior with a large negative magnetoresistance of ~ 65% near the magnetic transition temperature, together with positive MR near the field-induced spin-flop transitions, which can be understood in terms of the suppression of spin scattering by the magnetic field. © 2025, CC BY-NC-ND.

关键词： Gadolinium compounds

A-STEP: The AstroPix Sounding Rocket Technology Demonstration Payload

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arXiv 2024年

作者： Violette, Daniel P. Steinhebel, Amanda Roy, Abhradeep Boggs, Ryan Caputo, Regina Durachka, David Fukazawa, Yasushi Hashizume, Masaki Hesh, Scott Jadhav, Manoj Kierans, Carolyn Kumar, Kavic Kushima, Shin Leys, Richard Metcalfe, Jessica Metzler, Zachary Nakano, Norito Peric, Ivan Perkins, Jeremy Seo, Lindsey Taylor Shin, K.-W. Striebig, Nicolas Suda, Yusuke Tajima, Hiroyasu NASA Goddard Space Flight Center GreenbeltMD United States United States Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Japan NASA Wallops Flight Facility Wallops IslandVA United States Argonne National Laboratory LemontIL United States Department of Physics University of Maryland College ParkMD United States Institute for Space–Earth Environmental Research Nagoya University Aichi Japan ASIC and Detector Laboratory Karlsruhe Institute of Technology Karlsruhe Germany Institute for Particle Physics University of California Santa CruzCA United States

A next-generation medium-energy (100 keV to 100 MeV) gamma-ray observatory will greatly enhance the identification and characterization of multimessenger sources in the coming decade. Coupling gamma-ray spectroscopy, imaging, and polarization to neutrino and gravitational wave detections will develop our understanding of various astrophysical phenomena including compact object mergers, supernovae remnants, active galactic nuclei and gamma-ray bursts. An observatory operating in the MeV energy regime requires technologies that are capable of measuring Compton scattered photons and photons interacting via pair production. AstroPix is a monolithic high voltage CMOS active pixel sensor which enables future gamma-ray telescopes in this energy range. AstroPix’s design is iterating towards low-power (∼1.5 mW/cm2), high spatial (500 µm pixel pitch) and spectral (2 building block of future large area AstroPix instruments, such as ComPair-2 and AMEGO-X. This payload will be the first demonstration of AstroPix detectors operated in a space environment and will demonstrate the technology’s readiness for future astrophysical and nuclear physics applications. In this work, we overview the design and state of development of the A-STEP payload. Copyright © 2024, The Authors. All rights reserved.

关键词： Photons

A comprehensive review on natural convection in trapezoidal cavities with mono and hybrid nanofluids

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International Journal of Thermofluids 2025年 27卷

作者： Rashid, Farhan Lafta Alkhekany, Zainab Abdul Karim Eleiwi, Muhammad Asmail Bouabidi, Abdallah Ahmad, Shabbir Chibani, Atef Kezzar, Mohamed Kadhim, Saif Ali Askar, Ali Habeeb Hammoodi, Karrar A. Department of Petroleum Engineering College of EngineeringmUniversity of Kerbala Karbala56001 Iraq College of Engineering University of Warith Al-Anbiyaa Karbala56001 Iraq Electromechanical Engineering Department College of Engineering University of Samarra Samarra Iraq University of Gabes Avenue of Omar Ib-Elkhattab Gabes Zrig6023 Tunisia Graduate Program of Ocean Engineering School of Engineering Universidade Federal do Rio Grande Italia Avenue km 8 Rio Grande96201-900 Brazil Institute of Geophysics and Geomatics China University of Geosciences Wuhan430074 China Research Center in Industrial Technologies CRTI P.O.Box 64 Algiers Cheraga16014 Algeria Department of Mechanical Engineering University of 20 Aout 1955 El Hadaiek Road B. O. 26 Skikda21000 Algeria Technology Department Faculty of Technology 20 Aout 1955 University of Skikda PO Box 26 Skikda21000 Algeria Mechanical Engineering Department University of Technology- Iraq Baghdad Iraq Department of Fluid and Heat Engineering University of Miskolc Miskolc Hungary Institute of Physics and Electrical Engineering University of Miskolc Miskolc Hungary College of Engineering University of Al Maarif Al Anbar Iraq

This review synthesises advancements in natural convection within trapezoidal cavities using mono- and hybrid nanofluids, emphasising their geometric advantages for thermal management. Trapezoidal cavities promote asymmetric flow patterns that enhance heat transfer compared to conventional geometries, as demonstrated in applications like solar absorbers and electronic cooling. Through analysis of 50+ previous studies, the review identifies key trends: Hybrid nanofluids like Cu-Al₂O₃/water consistently outperform mono nanofluids in Nusselt number improvement, with gains exceeding 20 %. Inclined walls mitigate stagnant flow zones, though exact reduction rates vary with aspect ratio and nanoparticle concentration. Magnetic fields and porous media further modulate thermal performance, but trade-offs emerge between conductivity enhancement and viscosity penalties. This review provides a framework to optimise trapezoidal cavities with nanofluids for industrial deployment. © 2025 The Author(s)

关键词： Natural convection

Radon exhalation rate from the latex pillows and its potential exposure to users

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Radiation Medicine and Protection 2024年第4期5卷 238-242页

作者： Phachirarat Sola Kanokporn Boonsirichai Santi Raksawong Ritiron Samran Pimprapa Chaijak Hirofumi Tazoe Chutima Kranrod Rawiwan Kritsananuwat Sattawat Jongjitklang Vichai Puripunyavanich Masahiro Hosoda Waleeporn Pongkua Shinji Tokonami Thailand Institute of Nuclear Technology(Public Organization) Sai MunOngkharakNakhon Nayok26120Thailand Physics Program Faculty of Science and TechnologyMuban Chombueng Rajabhat UniversityRatchaburi70150Thailand Department of Biology Faculty of ScienceThaksin UniversityPhatthalung93210Thailand Institute of Radiation Emergency Medicine Hirosaki UniversityHirosaki Aomori036-8564Japan Nuclear Engineering Chulalongkorn UniversityPatumwanBangkok10330Thailand

Objective:To develop a new system to accurately measure the radon exhalation from the latex pillows,and to estimate its potential exposure to ***:The new system is composed of two loops,the first loop is designed to trap background radon and thoron until their levels are nearly zero,and the second loop is the measurement loop to detect radon and thoron exhalation rates from the ***:The results showed that mass radon exhalation rated ranged from 0.18 Bq·kg^(-1)·h^(-1) to 0.78 Bq·kg^(-1)·h^(-1),with an average of(0.36±0.17)Bq·kg^(-1)·h^(-1) in the 9 *** average annual effective dose to users in a model room was estimated to be(15.51±12.69)μSv by assuming two pillows was ***:These results demonstrate that the new system can effectively measure radon exhalation rates in latex pillows,and the potential exposure to radon exhalating from the pillows is very low.

关键词： Radon exhalation Latex pillow Annual effective dose

Application of 2-D and 3-D Geo-electrical Resistivity Tomography and Geotechnical Soil Evaluation for engineering Site Investigation:A Case Study of Okerenkoko Primary School,Warri-Southwest,Delta State,Nigeria

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Advances in Geological and Geotechnical engineering Research 2023年第2期5卷 1-23页

作者： U.Stanley Eze M.Edirin Okiotor J.E.Ighodalo B.Jennifer Owonaro A.Saleh Saleh A.Sikiru Jamiu Department of Earth Sciences Federal University of Petroleum ResourcesEffurun330102Nigeria Department of Marine Geology Nigeria Maritime UniversityOkerenkokoWarri SouthDelta State332105Nigeria Department of Physics(Applied Geophysics program) University of BeninBenin CityEdo State300213Nigeria Department of Petroleum Engineering and Geosciences Petroleum Training InstituteEffurun330102Nigeria

In the design of building structures,joint efforts must be decided to resolve the depth of competent layers across the intended site to safeguard the durability of civil engineering structures and to avert the disastrous consequences of structural failure and *** this study,an integrated methodology that employed DC resistivity tomography involving 2-D and 3-D techniques and geotechnical-soil analysis was used to evaluate subsoil conditions for engineering site investigation at Okerenkoko primary school,in the Warri-southwest area of Delta State,to adduce the phenomena responsible for the visible cracks/structural failure observed in the *** results obtained brought to light the geological structure beneath the subsurface,which consists of four geoelectric layers identified as topsoil,dry/lithified upper sandy layer,wet sand(water-saturated)and peat/clay/sandy clayey soil(highly water-saturated).The deeply-seated peat/clay materials(ρ≤20Ωm)were delineated in the study area to the depths of 17.1 m and 19.8 m from 2-D and 3-D tomography respectively.3-D images presented as horizontal depth slices revealed the dominance of very low resistivity materials ***/clay/sandy clay within the fourth,fifth and sixth layers at depths ranging from 8.68-12.5 m,12.5-16.9 m and 16.9-21.9 m *** dominance of mechanically unstable peat/clay/sandy clay layers beneath the subsurface,which are highly mobile in response to volumetric changes,is responsible for the noticeable cracks/failure detected on structures within the study *** observations were validated by a geotechnical test of soil samples in the study ***’s limits of the samples revealed plasticity indices of ***,the soil samples within the depth analyzed were representatives of sandy soil that does not possess any *** methods justifiably provided relevant information on the subsurface geology beneath the study site and should be appropriated as major tools for

关键词： 2D and 3D resistivity tomography engineering site/structure Atterberg limits Orthogonal lines Radar sounding

Comment on “Reconsidering nonlinear emergent inductance: Time-varying Joule heating and its impact on AC electrical response”

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Physical Review B 2025年第14期111卷 146401-146401页

作者： Tomoyuki Yokouchi Aki Kitaori Daiki Yamaguchi Naoya Kanazawa Max Hirschberger Naoto Nagaosa Yoshinori Tokura RIKEN Center for Emergent Matter Science (CEMS) Wako 351-0198 Japan Department of Applied Physics and Quantum Phase Electronics Center (QPEC) The University of Tokyo Tokyo 113-8656 Japan Institute of Engineering Innovation The University of Tokyo Tokyo 113-0032 Japan Institute of Industrial Science The University of Tokyo Tokyo 153-8505 Japan Fundamental Quantum Science Program TRIP Headquarters RIKEN Wako 351-0198 Japan Tokyo College The University of Tokyo Tokyo 113-8656 Japan

When noncollinear spin textures are driven by current, an emergent electric field arises due to the emergent electromagnetic induction. So far, this phenomenon has been reported in several materials, manifesting the current-nonlinear imaginary part of the complex impedance. Recently, Furuta et al. proposed a time-varying temperature increase due to Joule heating as an alternative explanation for these current-nonlinear complex impedances [Furuta et al., Phys. Rev. B 110, 174402 (2024)]. In this Comment, we demonstrate that the experimentally observed nonlinear complex impedances in helimagnets cannot be explained by the time-varying temperature increase. Instead, these dependencies of the imaginary part of the nonlinear impedance are consistent with the expected behavior in the theory of emergent electromagnetic induction.

关键词： Joule heating

Field-Dependent Magnetic Domain Behavior in van der Waals Fe3GeTe2

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arXiv 2022年

作者： Li, Yue Basnet, Rabindra Pandey, Krishna Hu, Jin Wang, Wei Ma, Xuedan McCray, Arthur R.C. Petford-Long, Amanda K. Phatak, Charudatta Materials Science Division Argonne National Laboratory LemontIL60439 United States Department of Physics University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Center for Nanoscale Materials Argonne National Laboratory LemontIL60439 United States Applied Physics Program Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States

Two-dimensional magnetic van der Waals (vdW) materials can show a variety of topological nontrivial spin textures, such as Bloch- or Néel-type stripe, skyrmion or bubble domains under certain external stimuli. It is critical to understand the magnetic domain behavior in vdW materials in order to control their size, and density in response to external stimuli such as electric and magnetic fields. Here we examine the magnetic field dependence of topologically non-trivial magnetization spin textures in vdW Fe3GeTe2. Néel-type stripe domains and skyrmions are formed depending on the magnetic field-cooling protocol used during in-situ Lorentz transmission electron microscopy (LTEM) experiments. Use of quantitative reconstruction of magnetic induction maps, and micromagnetic simulations, allow for understanding the LTEM results of Néel-type stripe domains as well as skyrmions. In addition, the deformation of skyrmion contrast is observed as a result of the introduction of an in-plane magnetic field. We demonstrate the stability of the stripe domains and skyrmions in response to externally applied magnetic field due to energy barrier for domain wall annihilation. Our results establish an understanding of the energy landscape that governs the behavior of the topologically non-trivial spin textures in vdW materials which can be harnessed for spintronic applications. Copyright © 2022, The Authors. All rights reserved.

关键词： Van der Waals forces

Thermal Hysteresis Behavior of Skyrmion Lattices in the van der Waals Ferromagnet Fe3GeTe2

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arXiv 2022年

作者： McCray, Arthur R.C. Li, Yue Basnet, Rabindra Pandey, Krishna Hu, Jin Phelan, Daniel Ma, Xuedan Petford-Long, Amanda K. Phatak, Charudatta Materials Science Division Argonne National Laboratory LemontIL60439 United States Applied Physics Program Northwestern University EvanstonIL60208 United States Department of Physics University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Center for Nanoscale Materials Argonne National Laboratory LemontIL60439 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States

Understanding the physics of phase transitions in two-dimensional (2D) systems underpins the research in diverse fields including statistical mechanics, quantum systems, nanomagnetism, and soft condensed matter. However, many fundamental aspects of 2D phase transitions are still not well understood, including the effects of interparticle potential, polydispersity, and particle shape. Magnetic skyrmions, which are non-trivial chiral spin structures, can be considered as quasi-particles that form two-dimensional lattices. Here we show, by real-space imaging using in situ cryo-Lorentz transmission electron microscopy coupled with machine learning, the ordering behavior of Néel skyrmion lattices in van der Waals Fe3GeTe2. We demonstrate a distinct change in the skyrmion size distribution during field-cooling, which leads to a loss of lattice order and an evolution of the skyrmion liquid phase. Remarkably, the lattice order is restored during field heating and demonstrates a thermal hysteresis. Our quantitative analysis explains this behavior based on the energy landscape of skyrmions and demonstrates the potential to control the lattice order in 2D phase transitions. Copyright © 2022, The Authors. All rights reserved.

关键词： Van der Waals forces