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arXiv 2024年

作者： Paraschos, Georgios Filippos Kim, J.-Y. Wielgus, M. Röder, J. Krichbaum, T.P. Ros, E. Agudo, I. Myserlis, I. Moscibrodzka, M. Traianou, E. Zensus, J.A. Blackburn, L. Chan, C.-K. Issaoun, S. Janssen, M. Johnson, M.D. Fish, V.L. Akiyama, K. Alberdi, A. Alef, W. Algaba, J.C. Anantua, R. Asada, K. Azulay, R. Bach, U. Baczko, A.-K. Ball, D. Baloković, M. Barrett, J. Bauböck, M. Benson, B.A. Bintley, D. Blundell, R. Bouman, K.L. Bower, G.C. Boyce, H. Bremer, M. Brinkerink, C.D. Brissenden, R. Britzen, S. Broderick, A.E. Broguiere, D. Bronzwaer, T. Bustamante, S. Byun, D.-Y. Carlstrom, J.E. Ceccobello, C. Chael, A. Chang, D.O. Chatterjee, K. Chatterjee, S. Chen, M.T. Chen, Y. Cheng, X. Cho, I. Christian, P. Conroy, N.S. Conway, J.E. Cordes, J.M. Crawford, T.M. Crew, G.B. Cruz-Osorio, A. Cui, Y. Dahale, R. Davelaar, J. De Laurentis, M. Deane, R. Dempsey, J. Desvignes, G. Dexter, J. Dhruv, V. Doeleman, S.S. Dougal, S. Dzib, S.A. Eatough, R.P. Emami, R. Falcke, H. Farah, J. Fomalont, E. Ford, H.A. Foschi, M. Fraga-Encinas, R. Freeman, W.T. Friberg, P. Fromm, C.M. Fuentes, A. Galison, P. Gammie, C.F. García, R. Gentaz, O. Georgiev, B. Goddi, C. Gold, R. Gómez-Ruiz, A.I. Gómez, J.L. Gu, M. Gurwell, M. Hada, K. Haggard, D. Haworth, K. Hecht, M.H. Hesper, R. Heumann, D. Ho, L.C. Ho, P. Honma, M. Huang, C.L. Huang, L. Hughes, D.H. Ikeda, S. Impellizzeri, C.M.V. Inoue, M. James, D.J. Jannuzi, B.T. Jeter, B. Jaing, W. Jiménez-Rosales, A. Jorstad, S. Joshi, A.V. Jung, T. Karami, M. Karuppusamy, R. Kawashima, T. Keating, G.K. Kettenis, M. Kim, D.-J. Kim, J. Kim, J. Kino, M. Koay, J.Y. Kocherlakota, P. Kofuji, Y. Koch, P.M. Koyama, S. Kramer, C. Kramer, J.A. Kramer, M. Kuo, C.-Y. La Bella, N. Lauer, T.R. Lee, D. Lee, S.-S. Leung, P.K. Levis, A. Li, Z. Lico, R. Lindahl, G. Lindqvist, M. Lisakov, M. Liu, J. Liu, K. Liuzzo, E. Lo, W.-P. Lobanov, A.P. Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Department of Astronomy and Atmospheric Sciences Kyungpook National University Daegu702-701 Korea Republic of Institute of Physics Silesian University in Opava Bezručovo nám. 13 OpavaCZ-746 01 Czech Republic Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Avenida Divina Pastora 7 Local 20 GranadaE-18012 Spain Radboud University P.O. Box 9010 Nijmegen6500 GL Netherlands Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States NASA Hubble Fellowship Program Einstein Fellow United States Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road WestfordMA01886 United States National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Physics Faculty of Science Universiti Malaya Kuala Lumpur50603 Malaysia Department of Physics & Astronomy The University of Texas at San Antonio One UTSA Circle San AntonioTX78249 United States Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Sec. 4 Roosevelt Rd. Taipei10617 Taiwan Departament d’Astronomia i Astrofísica Universitat de València C. Dr. Moliner 50 Burjassot ValènciaE-46100 Spain Observatori Astronòmic Universitat de València C. Catedrático José Beltrán 2 València PaternaE-46980 Spain Department of Space Earth and Environment Chalmers University of Technology Onsala Space Observatory OnsalaSE-43992 Sweden Yale C

Context. 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz. Aims. Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84. Methods. We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure. Results. We report the detection of a highly ordered, strong magnetic field around the central, supermassive black hole of 3C 84. The brightness temperature analysis suggests that the system is in equipartition. We also determined a turnover frequency of νm = (113 ± 4) GHz, a corresponding synchrotron self-absorbed magnetic field of BSSA = (2.9 ± 1.6) G, and an equipartition magnetic field of Beq = (5.2 ± 0.6) G. Three components are resolved with the highest fractional polarisation detected for this object (mnet = (17.0 ± 3.9)%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017-2018. We report a steeply negative slope of the spectrum at 228 GHz. We used these findings to test existing models of jet formation, propagation, and Faraday rotation in 3C 84. Conclusions. The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C 84. However,

关键词： Magnetic fields

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The thickness dependence of quantum oscillations in ferromagnetic Weyl metal SrRuO3

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npj Quantum Materials 2023年第1期8卷 1-10页

作者： Uddipta Kar Akhilesh Kr. Singh Chih-Yu Lin Bipul Das Cheng-Tung Cheng Wei-Li Lee Yu-Te Hsu M. Berben S. Wiedmann Song Yang Chun-Yen Lin Chia-Hung Hsu Wei-Cheng Lee Institute of Physics Academia Sinica Nankang Taipei 11529 Taiwan Nano Science and Technology Taiwan International Graduate Program Academia Sinica and National Taiwan university Taipei Taiwan Department of Physics National Taiwan University Taipei 10617 Taiwan High Field Magnet Laboratory (HFML-EMFL) Radboud University Toernooiveld 7 6525 ED Nijmegen The Netherlands Radboud University Institute for Molecules and Materials Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands Scientific Research Division National Synchrotron Radiation Research Center Hsinchu 30076 Taiwan Department of Physics Applied Physics and Astronomy Binghamton University Binghamton NY 13902 USA

In a thin Weyl semimetal, a thickness dependent Weyl-orbit quantum oscillation was proposed to exist, originating from a nonlocal cyclotron orbit via electron tunnelings between top and bottom Fermi-arc surface states. Here, magneto-transport measurements were carried out on untwinned Weyl metal SrRuO3thin films. In particular, quantum oscillations with a frequencyFs1≈ 30 T were identified, corresponding to a small Fermi pocket with a light effective mass. Its oscillation amplitude appears to be at maximum for thicknesses in a range of 10 to 20 nm, and the phase of oscillation exhibits a systematic change with film thickness. The constructed Landau fan diagram shows an unusual concave downward curvature in the 1/μ0Hn-ncurve, wherenis the Landau level index. From thickness and field-orientation dependence, theFs1oscillation is attributed to be of surface origin. Those findings can be understood within the framework of the Weyl-orbit quantum oscillation effect with non-adiabatic corrections.

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Extrusion of chromatin loops by a composite loop extrusion factor

arXiv

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arXiv 2021年

作者： Yan, Hao Surovtsev, Ivan Williams, Jessica F. Bailey, Mary Lou P. King, Megan C. Mochrie, Simon G.J. Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Cell Biology Yale School of Medicine New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Department of Molecular Cellular and Developmental Biology Yale University New HavenCT06520 United States

Chromatin loop extrusion by Structural Maintenance of Chromosome (SMC) complexes is thought to underlie intermediate-scale chromatin organization inside cells. Motivated by a number of experiments suggesting that nucleosomes may block loop extrusion by SMCs, such as cohesin and condensin complexes, we introduce and characterize theoretically a composite loop extrusion factor (composite LEF) model. In addition to an SMC complex that creates a chromatin loop by encircling two threads of DNA, this model includes a remodeling complex that relocates or removes nucleosomes as it progresses along the chromatin, and nucleosomes that block SMC translocation along the DNA. Loop extrusion is enabled by SMC motion along nucleosome-free DNA, created in the wake of the remodeling complex, while nucleosome re-binding behind the SMC acts as a ratchet, holding the SMC close to the remodeling complex. We show that, for a wide range of parameter values, this collection of factors constitutes a composite LEF that extrudes loops with a velocity, comparable to the velocity of remodeling complex translocation on chromatin in the absence of SMC, and much faster than loop extrusion by an isolated SMC that is blocked by nucleosomes. Copyright © 2021, The Authors. All rights reserved.

关键词： Chromosomes

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Elemental abundances of 44 very metal-poor stars determined from Subaru/IRD near-infrared spectra

arXiv

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arXiv 2025年

作者： Aoki, Wako Beers, Timothy C. Honda, Satoshi Matsuno, Tadafumi Placco, Vinicius M. Yoon, Jinmi Kuzuhara, Masayuki Harakawa, Hiroki Hirano, Teruyuki Kotani, Takayuki Kurokawa, Takashi Nishikawa, Jun Omiya, Masashi Tamura, Motohide Vievard, Sébastien National Astronomical Observatory 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program Graduate Institute for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Physics and Astronomy JINA Center for the Evolution of the Elements University of Notre Dame Notre DameIN46556 United States Nishi-Harima Astronomical Observatory Center for Astronomy University of Hyogo 407-2 Nishigaichi Sayo-cho Hyogo Sayo679-5313 Japan Astronomisches Rechen-Institut Zentrum für Astronomie der Universität Heidelberg Mönchhofstraße 12–14 Heidelberg69120 Germany NSF NOIRLab 950 N. Cherry Ave. TucsonAZ85719 United States Space Telescope Science Institute 3700 San Martin Dr. BaltimoreMD21218 United States Astrobiology Center 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Subaru Telescope 650 N. Aohoku Place HiloHI96720 United States Institute of Engineering Tokyo University of Agriculture and Technology 2-24-16 Nakacho Koganei Tokyo184-8588 Japan Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan

关键词： Supernovae

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The EB-correlation in Resolved Polarized Images: Connections to Astrophysics of Black Holes

arXiv

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arXiv 2023年

作者： Emami, Razieh Doeleman, Sheperd S. Wielgus, MacIek Chang, Dominic Chatterjee, Koushik Smith, Randall Liska, Matthew Steiner, James F. Ricarte, Angelo Narayan, Ramesh Tremblay, Grant Finkbeiner, Douglas Hernquist, Lars Chan, Chi-Kwan Blackburn, Lindy Prather, Ben S. Tiede, Paul Broderick, Avery E. Vogelsberger, Mark Alcock, Charles Roelofs, Freek Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States CCS-2 Los Alamos National Laboratory P.O. Box 1663 Los AlamosNM87545 United States Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Department of Physics and Astronomy University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States

We present an in-depth analysis of a newly proposed correlation function in visibility space, between the E and B modes of the linear polarization, hereafter the EB-correlation, for a set of time-averaged GRMHD simulations compared with the phase map from different semi-analytic models as well as the Event Horizon Telescope (EHT) 2017 data for M87∗source. We demonstrate that the phase map of the time-averaged EB-correlation contains novel information that might be linked to the BH spin, accretion state and the electron temperature. A detailed comparison with a semi-analytic approach with different azimuthal expansion modes shows that to recover the morphology of the real/imaginary part of the correlation function and its phase, we require higher orders of these azimuthal modes. To extract the phase features, we propose to use the Zernike polynomial reconstruction developing an empirical metric to break degeneracies between models with different BH spins that are qualitatively similar. We use a set of different geometrical ring models with various magnetic and velocity field morphologies and show that both the image space and visibility based EB-correlation morphologies in MAD simulations can be explained with simple fluid and magnetic field geometries as used in ring models. SANEs by contrast are harder to model, demonstrating that the simple fluid and magnetic field geometries of ring models are not sufficient to describe them owing to higher Faraday Rotation depths. A qualitative comparison with the EHT data demonstrates that some of the features in the phase of EB-correlation might be well explained by the current models for BH spins as well as electron temperatures, while others may require a larger theoretical surveys. © 2023, CC BY.

关键词： Polarization

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The First Detection of a Protostellar CO Outflow in the Small Magellanic Cloud with ALMA

arXiv

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arXiv 2022年

作者： Tokuda, Kazuki Zahorecz, Sarolta Kunitoshi, Yuri Higashino, Kosuke Tanaka, Kei E.I. Konishi, Ayu Suzuki, Taisei Kitano, Naoya Harada, Naoto Shimonishi, Takashi Neelamkodan, Naslim Fukui, Yasuo Kawamura, Akiko Onishi, Toshikazu Machida, Masahiro N. Department of Earth and Planetary Sciences Faculty of Science Kyushu University Fukuoka Nishi-ku819-0395 Japan National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Physics Graduate School of Science Osaka Metropolitan University 1-1 Gakuen-cho Naka-ku Sakai Osaka599-8531 Japan Center for Astrophysics and Space Astronomy University of Colorado Boulder BoulderCO80309 United States Department of Earth and Planetary Sciences Faculty of Sciences Kyushu University Fukuoka Nishi-ku819-0395 Japan Environmental Science Program Faculty of Science Niigata University Ikarashi-ninocho 8050 Nishi-ku Niigata950-2181 Japan Department of Physics United Arab Emirates University Al-Ain15551 United Arab Emirates Department of Physics Nagoya University Furo-cho Chikusa-ku Nagoya464-8601 Japan

Protostellar outflows are one of the most outstanding features of star formation. Observational studies over the last several decades have successfully demonstrated that outflows are ubiquitously associated with low- and high-mass protostars in the solar-metallicity Galactic conditions. However, the environmental dependence of protostellar outflow properties is still poorly understood, particularly in the low-metallicity regime. Here we report the first detection of a molecular outflow in the Small Magellanic Cloud with 0.2 Z, using Atacama Large Millimeter/submillimeter Array observations at a spatial resolution of 0.1 pc toward the massive protostar Y246. The bipolar outflow is nicely illustrated by high-velocity wings of CO(3–2) emission at & 15 km s−1. The evaluated properties of the outflow (momentum, mechanical force, etc.) are consistent with those of the Galactic counterparts. Our results suggest that the molecular outflows, i.e., the guidepost of the disk accretion at the small scale, might be universally associated with protostars across the metallicity range of ∼ 0.2–1 Z. © 2022, CC BY.

关键词： Metals

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Recent results on LIV studies using MAGIC telescopes from the observation of GRB 190114C

Recent results on LIV studies using MAGIC telescopes from th...

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37th International Cosmic Ray Conference, ICRC 2021

作者： D'Amico, Giacomo Kerszberg, Daniel Martínez, Manel Perennes, Cédric Rico, Javier Terzić, Tomislav Acciari, V.A. Ansoldi, S. Antonelli, L.A. Arbet Engels, A. Artero, M. Asano, K. Baack, D. Babić, A. Baquero, A. Barres de Almeida, U. Barrio, J.A. Batković, I. Becerra González, J. Bednarek, W. Bellizzi, L. Bernardini, E. Bernardos, M. Berti, A. Besenrieder, J. Bhattacharyya, W. Bigongiari, C. Biland, A. Blanch, O. Bökenkamp, H. Bonnoli, G. Bošnjak, Ž. Busetto, G. Carosi, R. Ceribella, G. Cerruti, M. Chai, Y. Chilingarian, A. Cikota, S. Colak, S.M. Colombo, E. Contreras, J.L. Cortina, J. Covino, S. D'Elia, V. Da Vela, P. Dazzi, F. De Angelis, A. De Lotto, B. Delfino, M. Delgado, J. Delgado Mendez, C. Depaoli, D. Di Pierro, F. Di Venere, L. Do Souto Espiñeira, E. Dominis Prester, D. Donini, A. Dorner, D. Doro, M. Elsaesser, D. Fallah Ramazani, V. Fattorini, A. Fonseca, M.V. Font, L. Fruck, C. Fukami, S. Fukazawa, Y. García López, R.J. Garczarczyk, M. Gasparyan, S. Gaug, M. Giglietto, N. Giordano, F. Gliwny, P. Godinović, N. Green, J.G. Green, D. Hadasch, D. Hahn, A. Heckmann, L. Herrera, J. Hoang, J. Hrupec, D. Hütten, M. Inada, T. Ishio, K. Iwamura, Y. Jiménez Martínez, I. Jormanainen, J. Jouvin, L. Karjalainen, M. Kobayashi, Y. Kubo, H. Kushida, J. Lamastra, A. Lelas, D. Leone, F. Lindfors, E. Linhoff, L. Lombardi, S. Longo, F. López-Coto, R. López-Moya, M. López-Oramas, A. Loporchio, S. Machado de Oliveira Fraga, B. Maggio, C. Majumdar, P. Makariev, M. Mallamaci, M. Maneva, G. Manganaro, M. Mannheim, K. Maraschi, L. Mariotti, M. Mazin, D. Menchiari, S. Mender, S. Mićanović, S. Miceli, D. Miener, T. Miranda, J.M. Mirzoyan, R. Molina, E. Moralejo, A. Morcuende, D. Moreno, V. Moretti, E. Nakamori, T. Nava, L. Neustroev, V. Nigro, C. Nilsson, K. Nishijima, K. Noda, K. Nozaki, S. Ohtani, Y. Oka, T. Otero-Santos, J. Paiano, S. Palatiello, M. Paneque, D. Paoletti, R. Paredes, J.M. Pavletić, L. Peñil, P. Persic, M. Pihet, M. Prada Moroni, P.G. Prandini, E. Instituto de Astrofísica de Canarias Dpto. de Astrofísica Universidad de La Laguna Tenerife La LagunaE-38200 Spain Università di Udine INFN Trieste UdineI-33100 Italy RomeI-00136 Italy ETH Zürich ZürichCH-8093 Switzerland Bellaterra BarcelonaE-08193 Spain The University of Tokyo Chiba Kashiwa277-8582 Japan Technische Universität Dortmund DortmundD-44221 Germany Zagreb10000 Croatia IPARCOS Institute EMFTEL Department Universidad Complutense de Madrid MadridE-28040 Spain URCA RJ Rio de Janeiro22290-180 Brazil Università di Padova INFN PadovaI-35131 Italy University of Lodz Faculty of Physics and Applied Informatics Department of Astrophysics Lodz90-236 Poland Università di Siena INFN Pisa SienaI-53100 Italy ZeuthenD-15738 Germany Max-Planck-Institut für Physik MünchenD-80805 Germany Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n Granada18008 Spain Università di Pisa INFN Pisa PisaI-56126 Italy Universitat de Barcelona ICCUB IEEC-UB BarcelonaE-08028 Spain Armenian MAGIC Group A. Alikhanyan National Science Laboratory Yerevan0036 Armenia Centro de Investigaciones Energéticas Medioambientales y Tecnológicas MadridE-28040 Spain INFN MAGIC Group INFN Sezione di Torino Università degli Studi di Torino TorinoI-10125 Italy INFN MAGIC Group INFN Sezione di Bari Dipartimento Interateneo di Fisica Università e del Politecnico di Bari BariI-70125 Italy Croatian MAGIC Group University of Rijeka Department of Physics Rijeka51000 Croatia Universität Würzburg WürzburgD-97074 Germany Finnish MAGIC Group Finnish Centre for Astronomy with ESO University of Turku TurkuFI-20014 Finland Departament de Física CERES-IEEC Universitat Autònoma de Barcelona BellaterraE-08193 Spain Japanese MAGIC Group: Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima739-8526 Japan Armenian MAGIC Group ICRANet-Armenia at NAS RA Yerevan0019 Armenia Split21000

On January 14, 2019, the most energetic photons ever observed from a gamma-ray burst were recorded by the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes, detecting GRB 190114C at TeV energies. We used this unique observation to probe an energy dependence of the speed of light in vacuo for photons, as predicted by several quantum gravity models. From a set of conservative assumptions on the possible intrinsic spectral and temporal evolution, competitive lower limits on the quadratic leading order modification of the speed of light were obtained. We performed the first Lorentz invariance violation test ever performed on a gamma-ray burst signal at TeV energies, which will serve as a stepping stone to future studies. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0)

关键词： Photons

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Alternation of Magnetic Anisotropy Accompanied by Metal-Insulator Transition in Strained Ultrathin Manganite Heterostructures

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Physical Review applied 2021年第6期15卷 064019-064019页

作者： Masaki Kobayashi Le Duc Anh Masahiro Suzuki Shingo Kaneta-Takada Yukiharu Takeda Shin-ichi Fujimori Goro Shibata Arata Tanaka Masaaki Tanaka Shinobu Ohya Atsushi Fujimori Department of Electrical Engineering and Information Systems The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan Center for Spintronics Research Network The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan Institute of Engineering Innovation Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan PRESTO JST 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan Department of Physics The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan Materials Sciences Research Center Japan Atomic Energy Agency Sayo-gun Hyogo 679-5148 Japan Department of Applied Physics Tokyo University of Science Katsushika Tokyo 125-8585 Japan Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima 739-8530 Japan Department of Applied Physics Waseda University Okubo Shinjuku Tokyo 169-8555 Japan

A fundamental understanding of the interfacial magnetic properties in ferromagnetic heterostructures is essential for utilizing ferromagnetic materials for spintronic device applications. Here, we investigate the interfacial magnetic and electronic structures of epitaxial single-crystalline LaAlO3(LAO)/La0.6Sr0.4MnO3(LSMO)/Nb:SrTiO3(Nb:STO) heterostructures with varying LSMO layer thicknesses, in which the magnetic anisotropy strongly changes with the LSMO thickness due to the delicate balance between strains originating from both the Nb:STO and LAO layers, using x-ray magnetic circular dichroism and photoemission spectroscopy. We successfully detect the clear change of the magnetic behavior of the Mn ions concomitant with the thickness-dependent metal-insulator transition. Our results suggest that the double-exchange interaction induces ferromagnetism in the metallic LSMO film under tensile strain caused by the STO substrate, while the superexchange interaction determines the magnetic behavior in the insulating LSMO film under compressive strain originating from the top LAO layer. The change in strain, depending on LSMO layer thickness, is confirmed by scanning transmission electron microscopy. Based on those findings, the formation of a magnetic dead layer near the LAO/LSMO interface is attributed to competition between the superexchange interaction via Mn 3d3z2−r2 orbitals under compressive strain and the double-exchange interaction via the 3dx2−y2 orbitals. These findings provide key aspects of ferromagnetic oxide heterostructures for the development of spintronic device applications.

关键词： Electronic structure Ferromagnetism Magnetic anisotropy Metal-insulator transition Spintronics Transition metal oxides Photoemission spectroscopy X-ray magnetic circular dichroism

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The Duel of Magnetic Interactions & Structural Instabilities: Itinerant Frustration in the Triangular Lattice Compound LiCrSe2

arXiv

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arXiv 2022年

作者： Nocerino, E. Kobayashi, S. Witteveen, C. Forslund, O.K. Matsubara, N. Tang, C. Matsukawa, T. Hoshikawa, A. Koda, A. Yoshimura, K. Umegaki, I. Sassa, Y. von Rohr, F.O. Pomjakushin, V. Brewer, J.H. Sugiyama, J. Månsson, M. KTH Royal Institute of Technology Department of Applied Physics Alba Nova University Center StockholmSE-114 21 Sweden 1-1-1 Kouto Sayo679-5198 Japan Department of Quantum Matter Physics University of Geneva 24 Quai Ernest-Ansermet Geneva 41211 Switzerland Department of Physics University of Zürich Winterthurerstr. 190 Zürich8057 Switzerland Chalmers University of Technology Department of Physics GöteborgSE-412 96 Sweden Diamond House Harwell Science and Innovation Campus Fermi Ave DidcotOX11 0DE United Kingdom Frontier Research Center for Applied Atomic Sciences Ibaraki University 162-1 Shirakata Ibaraki Tokai319-1106 Japan Ibaraki Tsukuba305-0801 Japan Department of Materials Structure Science The Graduate University for Advanced Studies Ibaraki Tsukuba305-0801 Japan Department of Chemistry Graduate School of Science Kyoto University Kyoto606-8502 Japan Muon Science Laboratory Institute of Materials Structure Science KEK Ibaraki Tokai319-1106 Japan Laboratory for Neutron Scattering and Imaging Paul Scherrer Institute PSI Villigen5232 Switzerland Department of Physics and Astronomy University of British Columbia VancouverBCV6T 1Z1 Canada TRIUMF 4004 Wesbrook Mall VancouverBCV6T 2A3 Canada Ibaraki Tokai319-1106 Japan Advanced Science Research Center Japan Atomic Energy Agency Ibaraki Tokai319-1195 Japan

The recent synthesis of the chromium selenide compound LiCrSe2 constitutes a valuable addition to the ensemble of two-dimensional triangular lattice antiferromagnets (2D-TLA). In this work we present the very first comprehensive study of the combined low temperature nuclear and magnetic structure established in this material. Details on the connection between Li-ion dynamics and structural changes are also presented along with a direct link between atomic structure and spin order via a strong magnetoelastic coupling. LiCrSe2 was found to undergo a first order structural transition from a trigonal crystal system with space group P3¯m1 to a monoclinic one with space group C2/m at Ts = 30 K. Such restructuring of the lattice is accompanied by a magnetic transition at TN = 30 K, with the formation of a complex spin arrangement for the Cr3+ moments. Refinement of the magnetic structure with neutron diffraction data and complementary muon spin rotation analysis reveal the presence of two incommensurate magnetic domains with a up-up-down-down arrangement of the spins with ferromagnetic (FM) double chains coupled antiferromagnetically (AFM). In addition to this unusual arrangement, the spin axial vector is modulated both in direction and modulus, resulting in a spin density wave-like order with periodic suppression of the Cr moment along the chains. This behavior is believed to appear as a result of strong competition between direct exchange AFM and superexchange FM couplings established between both nearest neighbor and next nearest neighbor Cr3+ ions. We finally conjecture that the resulting magnetic order is stabilized via subtle vacancy/charge order within the Li layers, potentially causing a mix of two co-existing magnetic phases within the sample. © 2022, CC BY.

关键词： Chromium compounds

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Absolute dimensions of solar-type eclipsing binaries. NY Hya: A test for magnetic stellar evolution models

arXiv

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arXiv 2024年

作者： Hinse, T.C. Baştürk, Ö. Southworth, J. Feiden, G.A. Tregloan-Reed, J. Kostov, V.B. Livingston, J. Esmer, E.M. Yılmaz, Mesut Yalçınkaya, Selçuk Torun, Şeyma Vos, J. Evans, D.F. Morales, J.C. Wolf, J.C.A. Olsen, E.H. Clausen, J.V. Helt, B.E. Lý, C.T.K. Stahl, O. Wells, R. Herath, M. Jørgensen, U.G. Dominik, M. Skottfelt, J. Peixinho, N. Longa-Peña, P. Kim, Y. Kim, H.-E. Yoon, T.S. Alrebdi, H.I. Zotos, E.E. University of Southern Denmark Department of Physics Chemistry and Pharmacy SDU-Galaxy Campusvej 55 Odense M5230 Denmark Ankara University Faculty of Science Department of Astronomy and Space Sciences Tandogan AnkaraTR-06100 Turkey İncek Blvd. Ahlatlıbel AnkaraTR-06837 Turkey Astrophysics Group Keele University StaffordshireST5 5BG United Kingdom Department of Physics & Astronomy University of North Georgia DahlonegaGA30597 United States Instituto de Investigación en Astronomia y Ciencias Planetarias Universidad de Atacama Avenida Copayapu 485 Atacama Copiapó Chile NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States SETI Institute 189 Bernardo Ave Suite 200 Mountain ViewCA94043 United States Astrobiology Center NINS 2-21-1 Osawa Mitaka Tokyo181-8588 Japan National Astronomical Observatory of Japan NINS 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Ankara University Graduate School of Natural and Applied Sciences Department of Astronomy and Space Sciences Tandoğan AnkaraTR-06100 Turkey Astronomical Institute of the Czech Academy of Sciences OndřejovCZ-251 65 Czech Republic Campus UAB c/Can Magrans s/n Bellaterra BarcelonaE-08193 Spain Edifici RDIT Campus UPC Castelldefels BarcelonaE-08860 Spain Niels Bohr Institute University of Copenhagen Jagtvej 155 CopenhagenDK-2200 Denmark Chungnam National University Department of Astronomy Space Science and Geology Daejeon Korea Republic of Landessternwarte Zentrum für Astronomie der Universität Heidelberg HeidelbergD-69117 Germany Center for Space and Habitability University of Bern Gesellschaftsstrasse 6 Bern3012 Switzerland McGill Space Institute McGill University 3550 University Street MontrealQCH3A 2A7 Canada Department of Astronomy Arthur C. Clarke Institute for Modern Technologies Moratuwa0272 Sri Lanka Centre f

Context. The binary star NY Hya is a bright, detached, double-lined eclipsing system with an orbital period of just under five days with two components each nearly identical to the Sun and located in the solar neighbourhood. Aims. The objective of this study is to test and confront various stellar evolution models for solar-type stars based on accurate measurements of stellar mass and radius. Methods. We present new ground-based spectroscopic and photometric as well as high-precision space-based photometric and astrometric data from which we derive orbital as well as physical properties of the components via the method of least-squares minimisation based on a standard binary model valid for two detached components. Classic statistical techniques were invoked to test the significance of model parameters. Additional empirical evidence was compiled from the public domain;the derived system properties were compared with archival broad-band photometry data enabling a measurement of the system's spectral energy distribution that allowed an independent estimate of stellar properties. We also utilised semi-empirical calibration methods to derive atmospheric properties from Strömgren photometry and related colour indices. Results. We measured (percentages are fractional uncertainties) masses, radii, and effective temperatures of the two stars in NY Hya and found them to be MA = 1.1605 ± 0.0090 M☉ (0.78%), RA = 1.407 ± 0.015 R☉ (1.1%), Teff,A = 5595 ± 61 K (1.09%), MB = 1.1678 ± 0.0096 M☉ (0.82%), RB = 1.406 ± 0.017 R☉ (1.2%), and Teff,B = 5607 ± 61 K (1.09%). The atmospheric properties from Strömgren photometry agree well with spectroscopic results. No evidence was found for nearby companions from high-resolution imaging. A detailed analysis of space-based data revealed a small but significant eccentricity (e cos ω) of the orbit. The spectroscopic and frequency analysis on photometric time series data reveal evidence of clear photospheric activity on both components likely i

关键词： Photometry

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