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Ghiringhelli LM, Baldauf C, Bereau T, Brockhauser S, Carbogno C, Chamanara J, Cozzini S, Curtarolo S, Draxl C, Dwaraknath S, Fekete Á, Kermode J, Koch CT, Kühbach M, Ladines AN, Lambrix P, Himmer MO, Levchenko SV, Oliveira M, Michalchuk A, Miller RE, Onat B, Pavone P, Pizzi G, Regler B, Rignanese GM, Schaarschmidt J, Scheidgen M, Schneidewind A, Sheveleva T, Su C, Usvyat D, Valsson O, Wöll C, Scheffler M. Shared metadata for data-centric materials science. Sci Data 2023; 10:626. [PMID: 37709811 PMCID: PMC10502089 DOI: 10.1038/s41597-023-02501-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/23/2023] [Indexed: 09/16/2023] Open
Affiliation(s)
- Luca M Ghiringhelli
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany.
- The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin, Berlin, Germany.
- Department of Materials Science and Engineering, Friedrich-Alexander Universität, Erlangen-Nürnberg, Germany.
| | - Carsten Baldauf
- Fritz-Haber-Institut of the Max-Planck-Gesellschaft, Berlin, Germany
| | - Tristan Bereau
- Van't Hoff Institute for Molecular Sciences and Informatics Institute, University of Amsterdam, Amsterdam, 1098 XH, The Netherlands
| | - Sandor Brockhauser
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christian Carbogno
- The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin, Berlin, Germany
| | - Javad Chamanara
- TIB - Leibniz Information Centre for Science and Technology and University Library, 30167, Hanover, Germany
| | - Stefano Cozzini
- AREA Science Park, località Padriciano, 34149, Trieste, Italy
| | - Stefano Curtarolo
- Center for Autonomous Materials Design and Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
| | - Claudia Draxl
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
- The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin, Berlin, Germany
| | | | - Ádám Fekete
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - James Kermode
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Christoph T Koch
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Markus Kühbach
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Alvin Noe Ladines
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Patrick Lambrix
- Department of Computer and Information Science and The Swedish e-Science Research Centre, Linköping University, Linköping, Sweden
| | - Maja-Olivia Himmer
- The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sergey V Levchenko
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Micael Oliveira
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - Adam Michalchuk
- Federal Institute for Materials Research and Testing (BAM), 12489, Berlin, Germany
- School of Chemistry, University of Birmingham, B15 2TT, Edgbaston, Birmingham, UK
| | - Ronald E Miller
- Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Berk Onat
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Pasquale Pavone
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Giovanni Pizzi
- Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
- Laboratory for Materials Simulations (LMS), Paul Scherrer Institut (PSI), CH-5232, Villigen, Switzerland
| | - Benjamin Regler
- The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin, Berlin, Germany
| | - Gian-Marco Rignanese
- Institute of Condensed Matter and Nanosciences (IMCN), UCLouvain, Chemin des Étoiles 8, B-1348, Louvain-la-Neuve, Belgium
| | - Jörg Schaarschmidt
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Karlsruhe, Germany
| | - Markus Scheidgen
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Astrid Schneidewind
- Jülich Center for Neutron Science at MLZ, Forschungszentrum Jülich GmbH, Lichtenbergstrase 1, 85748, Garching, Germany
| | - Tatyana Sheveleva
- TIB - Leibniz Information Centre for Science and Technology and University Library, 30167, Hanover, Germany
| | - Chuanxun Su
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, People's Republic of China
| | - Denis Usvyat
- Chemistry Department, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Omar Valsson
- Department of Chemistry, University of North Texas, Denton, TX, 76201, USA
| | - Christof Wöll
- Institute of Functional Interfaces, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Karlsruhe, Germany
| | - Matthias Scheffler
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
- The NOMAD Laboratory at the Fritz-Haber-Institut of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin, Berlin, Germany
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2
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Teixeira Parente M, Brandl G, Franz C, Stuhr U, Ganeva M, Schneidewind A. Active learning-assisted neutron spectroscopy with log-Gaussian processes. Nat Commun 2023; 14:2246. [PMID: 37076453 PMCID: PMC10115805 DOI: 10.1038/s41467-023-37418-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 03/16/2023] [Indexed: 04/21/2023] Open
Abstract
Neutron scattering experiments at three-axes spectrometers (TAS) investigate magnetic and lattice excitations by measuring intensity distributions to understand the origins of materials properties. The high demand and limited availability of beam time for TAS experiments however raise the natural question whether we can improve their efficiency and make better use of the experimenter's time. In fact, there are a number of scientific problems that require searching for signals, which may be time consuming and inefficient if done manually due to measurements in uninformative regions. Here, we describe a probabilistic active learning approach that not only runs autonomously, i.e., without human interference, but can also directly provide locations for informative measurements in a mathematically sound and methodologically robust way by exploiting log-Gaussian processes. Ultimately, the resulting benefits can be demonstrated on a real TAS experiment and a benchmark including numerous different excitations.
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Affiliation(s)
- Mario Teixeira Parente
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Garching, Germany.
| | - Georg Brandl
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Garching, Germany
| | - Christian Franz
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Garching, Germany
| | - Uwe Stuhr
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute (PSI), Villigen, Switzerland
| | - Marina Ganeva
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Garching, Germany.
| | - Astrid Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Garching, Germany
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3
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Qin Y, Shen Y, Liu C, Wo H, Gao Y, Feng Y, Zhang X, Ding G, Gu Y, Wang Q, Shen S, Walker HC, Bewley R, Xu J, Boehm M, Steffens P, Ohira-Kawamura S, Murai N, Schneidewind A, Tong X, Chen G, Zhao J. Field-tuned quantum effects in a triangular-lattice Ising magnet. Sci Bull (Beijing) 2022; 67:38-44. [DOI: 10.1016/j.scib.2021.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/17/2021] [Accepted: 08/13/2021] [Indexed: 11/24/2022]
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4
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Liu B, Wang L, Radelytskyi I, Zhang Y, Meven M, Deng H, Zhu F, Su Y, Zhu X, Tan S, Schneidewind A. Neutron scattering study of commensurate magnetic ordering in single crystal CeSb 2. J Phys Condens Matter 2020; 32:405605. [PMID: 32526723 DOI: 10.1088/1361-648x/ab9bcd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
Temperature and field-dependent magnetizationM(T,H ) measurements and neutron scattering study of a single crystal CeSb2are presented. Several anomalies in magnetization curves have been confirmed, i.e., at 15.6 K, 12 K, and 9.8 K, respectively. These three transitions are all metamagnetic transitions, which shift to lower temperatures as the magnetic field increases. In contrast to the previous studies that the anomaly at 15.6 K has been suggested as paramagnetic to ferromagnetic phase transition, in our measurement no hysteresis loop around zero field with eitherH∥corH ⊥ chas been observed. The anomaly located at around 12 K is antiferromagnetic-like transition, and this turning point will clearly split into two when the magnetic fieldH⩾ 2 kOe. A neutron scattering study reveals that the low temperature ground state of CeSb2orders magnetically with commensurate propagation wave vectorsk= (-1, ±1/6, 0) andk= (±1/6, -1, 0), with phase transition temperatureTC∼ 9.8 K.
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Affiliation(s)
- Benqiong Liu
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics (CAEP), Mianyang 621900, People's Republic of China
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Liming Wang
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Dongguan Neutron Science Center, Dongguan 523803, People's Republic of China
- Jülich Center for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Igor Radelytskyi
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Yun Zhang
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, People's Republic of China
| | - Martin Meven
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
- Institute of Crystallography, RWTH Aachen University, Aachen, Germany
| | - Hao Deng
- Institute of Crystallography, RWTH Aachen University, Aachen, Germany
| | - Fengfeng Zhu
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Yixi Su
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Xiegang Zhu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, People's Republic of China
| | - Shiyong Tan
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, People's Republic of China
| | - Astrid Schneidewind
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85748 Garching, Germany
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5
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Shen S, Zhang X, Wo H, Shen Y, Feng Y, Schneidewind A, Čermák P, Wang W, Zhao J. Neutron Spin Resonance in the Heavily Hole-Doped KFe_{2}As_{2} Superconductor. Phys Rev Lett 2020; 124:017001. [PMID: 31976731 DOI: 10.1103/physrevlett.124.017001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Indexed: 06/10/2023]
Abstract
We report high-resolution neutron scattering measurements of the low energy spin fluctuations of KFe_{2}As_{2}, the end member of the hole-doped Ba_{1-x}K_{x}Fe_{2}As_{2} family with only hole pockets, above and below its superconducting transition temperature T_{c} (∼3.5 K). Our data reveal clear spin fluctuations at the incommensurate wave vector (0.5±δ, 0, L), (δ=0.2) (1-Fe unit cell), which exhibit L-modulation peaking at L=0.5. Upon cooling to the superconducting state, the incommensurate spin fluctuations gradually open a spin gap and form a sharp spin resonance mode. The incommensurability (2δ=0.4) of the resonance mode (∼1.2 meV) is considerably larger than the previously reported value (2δ≈0.32) at higher energies (≥∼6 meV). The determination of the momentum structure of spin fluctuation in the low energy limit allows a direct comparison with the realistic Fermi surface and superconducting gap structure. Our results point to an s-wave pairing with a reversed sign between the hole pockets near the zone center in KFe_{2}As_{2}.
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Affiliation(s)
- Shoudong Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Xiaowen Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Hongliang Wo
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yao Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yu Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - A Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany
| | - P Čermák
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany
| | - Wenbin Wang
- Institute of Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China
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Song Y, Wang W, Van Dyke JS, Pouse N, Ran S, Yazici D, Schneidewind A, Čermák P, Qiu Y, Maple MB, Morr DK, Dai P. Nature of the spin resonance mode in CeCoIn 5. Commun Phys 2020; 3:10.1038/s42005-020-0365-8. [PMID: 33655080 PMCID: PMC7919742 DOI: 10.1038/s42005-020-0365-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
Spin-fluctuation-mediated unconventional superconductivity can emerge at the border of magnetism, featuring a superconducting order parameter that changes sign in momentum space. Detection of such a sign-change is experimentally challenging, since most probes are not phase-sensitive. The observation of a spin resonance mode (SRM) from inelastic neutron scattering is often seen as strong phase-sensitive evidence for a sign-changing superconducting order parameter, by assuming the SRM is a spin-excitonic bound state. Here we show that for the heavy fermion superconductor CeCoIn5, its SRM defies expectations for a spin-excitonic bound state, and is not a manifestation of sign-changing superconductivity. Instead, the SRM in CeCoIn5 likely arises from a reduction of damping to a magnon-like mode in the superconducting state, due to its proximity to magnetic quantum criticality. Our findings emphasize the need for more stringent tests of whether SRMs are spin-excitonic, when using their presence to evidence sign-changing superconductivity.
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Affiliation(s)
- Yu Song
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - Weiyi Wang
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - John S. Van Dyke
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Naveen Pouse
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
- Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sheng Ran
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
- Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093, USA
| | - Duygu Yazici
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
- Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093, USA
| | - A. Schneidewind
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
| | - Petr Čermák
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
- Present address: Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
| | - Y. Qiu
- NIST center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - M. B. Maple
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
- Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093, USA
| | - Dirk K. Morr
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
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7
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Chen T, Chen Y, Tam DW, Gao B, Qiu Y, Schneidewind A, Radelytskyi I, Prokes K, Chi S, Matsuda M, Broholm C, Dai P. Anisotropic effect of a magnetic field on the neutron spin resonance in FeSe. Phys Rev B 2020; 101:10.1103/physrevb.101.140504. [PMID: 33655092 PMCID: PMC7918269 DOI: 10.1103/physrevb.101.140504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We use inelastic neutron scattering to study the effect of a magnetic field on the neutron spin resonance (E r = 3.6 meV) of superconducting FeSe (T c = 9 K). While a field aligned along the in-plane direction broadens and suppresses the resonance, a c-axis aligned field does so much more efficiently, consistent with the anisotropic field-induced suppression of the superfluid density from the heat capacity measurements. These results suggest that the resonance in FeSe is associated with the superconducting electrons arising from orbital selective quasiparticle excitations between the hole and electron Fermi surfaces.
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Affiliation(s)
- Tong Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Youzhe Chen
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - David W. Tam
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Bin Gao
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Astrid Schneidewind
- Jülich Center for Neutron Sciences, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
| | - Igor Radelytskyi
- Jülich Center for Neutron Sciences, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
| | - Karel Prokes
- Helmholtz Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Masaaki Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Collin Broholm
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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8
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Niklowitz PG, Hirschberger M, Lucas M, Cermak P, Schneidewind A, Faulhaber E, Mignot JM, Duncan WJ, Neubauer A, Pfleiderer C, Grosche FM. Ultrasmall Moment Incommensurate Spin Density Wave Order Masking a Ferromagnetic Quantum Critical Point in NbFe_{2}. Phys Rev Lett 2019; 123:247203. [PMID: 31922868 DOI: 10.1103/physrevlett.123.247203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Indexed: 06/10/2023]
Abstract
In the metallic magnet Nb_{1-y}Fe_{2+y}, the low temperature threshold of ferromagnetism can be investigated by varying the Fe excess y within a narrow homogeneity range. We use elastic neutron scattering to track the evolution of magnetic order from Fe-rich, ferromagnetic Nb_{0.981}Fe_{2.019} to approximately stoichiometric NbFe_{2}, in which we can, for the first time, characterize a long-wavelength spin density wave state burying a ferromagnetic quantum critical point. The associated ordering wave vector q_{SDW}=(0,0,l_{SDW}) is found to depend significantly on y and T, staying finite but decreasing as the ferromagnetic state is approached. The phase diagram follows a two-order-parameter Landau theory, for which all of the coefficients can now be determined. Our findings suggest that the emergence of spin density wave order cannot be attributed to band structure effects alone. They indicate a common microscopic origin of both types of magnetic order and provide strong constraints on related theoretical scenarios based on, e.g., quantum order by disorder.
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Affiliation(s)
- P G Niklowitz
- Department of Physics, Royal Holloway, University of London, Egham TW20 0EX, United Kingdom
| | - M Hirschberger
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - M Lucas
- Department of Physics, Royal Holloway, University of London, Egham TW20 0EX, United Kingdom
| | - P Cermak
- Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16 Praha, Czech Republic
| | - A Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - E Faulhaber
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - J-M Mignot
- Laboratoire Léon Brillouin (CEA-CNRS), CEA Saclay, F-91911 Gif-sur-Yvette, France
| | - W J Duncan
- Department of Physics, Royal Holloway, University of London, Egham TW20 0EX, United Kingdom
| | - A Neubauer
- Physik Department E21, Technische Universität München, 85748 Garching, Germany
| | - C Pfleiderer
- Physik Department E21, Technische Universität München, 85748 Garching, Germany
| | - F M Grosche
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
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9
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Shen Y, Liu C, Qin Y, Shen S, Li YD, Bewley R, Schneidewind A, Chen G, Zhao J. Intertwined dipolar and multipolar order in the triangular-lattice magnet TmMgGaO 4. Nat Commun 2019; 10:4530. [PMID: 31594940 PMCID: PMC6783407 DOI: 10.1038/s41467-019-12410-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 09/09/2019] [Indexed: 11/09/2022] Open
Abstract
A phase transition is often accompanied by the appearance of an order parameter and symmetry breaking. Certain magnetic materials exhibit exotic hidden-order phases, in which the order parameters are not directly accessible to conventional magnetic measurements. Thus, experimental identification and theoretical understanding of a hidden order are difficult. Here we combine neutron scattering and thermodynamic probes to study the newly discovered rare-earth triangular-lattice magnet TmMgGaO4. Clear magnetic Bragg peaks at K points are observed in the elastic neutron diffraction measurements. More interesting, however, is the observation of sharp and highly dispersive spin excitations that cannot be explained by a magnetic dipolar order, but instead is the direct consequence of the underlying multipolar order that is "hidden" in the neutron diffraction experiments. We demonstrate that the observed unusual spin correlations and thermodynamics can be accurately described by a transverse field Ising model on the triangular lattice with an intertwined dipolar and ferro-multipolar order.
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Affiliation(s)
- Yao Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Changle Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Yayuan Qin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Shoudong Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Yao-Dong Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.,Department of Physics, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Robert Bewley
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom
| | - Astrid Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748, Garching, Germany
| | - Gang Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China. .,Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China. .,Center for Field Theory and Particle Physics, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
| | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
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10
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Jenni K, Kunkemöller S, Brüning D, Lorenz T, Sidis Y, Schneidewind A, Nugroho AA, Rosch A, Khomskii DI, Braden M. Interplay of Electronic and Spin Degrees in Ferromagnetic SrRuO_{3}: Anomalous Softening of the Magnon Gap and Stiffness. Phys Rev Lett 2019; 123:017202. [PMID: 31386396 DOI: 10.1103/physrevlett.123.017202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Indexed: 06/10/2023]
Abstract
The magnon dispersion of ferromagnetic SrRuO_{3} was studied by inelastic neutron scattering experiments on single crystals as a function of temperature. Even at low temperature the magnon modes exhibit substantial broadening pointing to strong interaction with charge carriers. We find an anomalous temperature dependence of both the magnon gap and the magnon stiffness, which soften upon cooling in the ferromagnetic phase. Both effects trace the temperature dependence of the anomalous Hall effect and can be attributed to the impact of Weyl points, which results in the same relative renormalization in the spin stiffness and magnon gap.
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Affiliation(s)
- K Jenni
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - S Kunkemöller
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - D Brüning
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - T Lorenz
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - Y Sidis
- Laboratoire Léon Brillouin, C.E.A./C.N.R.S., F-91191 Gif-sur-Yvette CEDEX, France
| | - A Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstraße 1, 85748 Garching, Germany
| | - A A Nugroho
- Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jalan Ganesha 10, 40132 Bandung, Indonesia
| | - A Rosch
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77a, D-50937 Köln, Germany
| | - D I Khomskii
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - M Braden
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
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11
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Chen T, Chen Y, Kreisel A, Lu X, Schneidewind A, Qiu Y, Park JT, Perring TG, Stewart JR, Cao H, Zhang R, Li Y, Rong Y, Wei Y, Andersen BM, Hirschfeld PJ, Broholm C, Dai P. Anisotropic spin fluctuations in detwinned FeSe. Nat Mater 2019; 18:709-716. [PMID: 31110345 PMCID: PMC7895486 DOI: 10.1038/s41563-019-0369-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 04/10/2019] [Indexed: 05/05/2023]
Abstract
Superconductivity in FeSe emerges from a nematic phase that breaks four-fold rotational symmetry in the iron plane. This phase may arise from orbital ordering, spin fluctuations or hidden magnetic quadrupolar order. Here we use inelastic neutron scattering on a mosaic of single crystals of FeSe, detwinned by mounting on a BaFe2As2 substrate to demonstrate that spin excitations are most intense at the antiferromagnetic wave vectors QAF = (±1, 0) at low energies E = 6-11 meV in the normal state. This two-fold (C2) anisotropy is reduced at lower energies, 3-5 meV, indicating a gapped four-fold (C4) mode. In the superconducting state, however, the strong nematic anisotropy is again reflected in the spin resonance (E = 3.6 meV) at QAF with incommensurate scattering around 5-6 meV. Our results highlight the extreme electronic anisotropy of the nematic phase of FeSe and are consistent with a highly anisotropic superconducting gap driven by spin fluctuations.
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Affiliation(s)
- Tong Chen
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - Youzhe Chen
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - Andreas Kreisel
- Institut für Theoretische Physik, Universität Leipzig, Leipzig, Germany
| | - Xingye Lu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing, China.
| | - Astrid Schneidewind
- Forschungszentrum Jülich GmbH, Jülich Center for Neutron Sciences at MLZ, Garching, Germany
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - J T Park
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, Germany
| | - Toby G Perring
- ISIS Facility, STFC Rutherford-Appleton Laboratory, Didcot, UK
| | - J Ross Stewart
- ISIS Facility, STFC Rutherford-Appleton Laboratory, Didcot, UK
| | - Huibo Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Rui Zhang
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - Yu Li
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - Yan Rong
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing, China
| | - Yuan Wei
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Brian M Andersen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - P J Hirschfeld
- Department of Physics, University of Florida, Gainesville, FL, USA
| | - Collin Broholm
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX, USA.
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing, China.
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12
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Wang J, Ran K, Li S, Ma Z, Bao S, Cai Z, Zhang Y, Nakajima K, Ohira-Kawamura S, Čermák P, Schneidewind A, Savrasov SY, Wan X, Wen J. Evidence for singular-phonon-induced nematic superconductivity in a topological superconductor candidate Sr 0.1Bi 2Se 3. Nat Commun 2019; 10:2802. [PMID: 31243284 PMCID: PMC6594966 DOI: 10.1038/s41467-019-10942-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 06/13/2019] [Indexed: 11/13/2022] Open
Abstract
Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent s-wave pairing function, due to the isotropic interactions between electrons and phonons along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr0.1Bi2Se3, a prime candidate for realizing topological superconductivity by doping the topological insulator Bi2Se3, we find that there exist highly anisotropic phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the [001] direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic p-wave nematic superconducting pairing in the MxBi2Se3 (M = Cu, Sr, Nb) superconductor family. Therefore, we show these superconductors to be example systems where electron-phonon interaction can induce more exotic superconducting pairing than the s-wave, consistent with the topological superconductivity.
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Affiliation(s)
- Jinghui Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Kejing Ran
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Shichao Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Zhen Ma
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Song Bao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Zhengwei Cai
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Youtian Zhang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Kenji Nakajima
- J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | | | - P Čermák
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748, Garching, Germany
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics Charles University, Ke Karlovu 5, 121 16, Praha, Czech Republic
| | - A Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748, Garching, Germany
| | - Sergey Y Savrasov
- Department of Physics, University of California, Davis, CA, 95616, USA
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - Jinsheng Wen
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
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13
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Li Y, Bachus S, Liu B, Radelytskyi I, Bertin A, Schneidewind A, Tokiwa Y, Tsirlin AA, Gegenwart P. Rearrangement of Uncorrelated Valence Bonds Evidenced by Low-Energy Spin Excitations in YbMgGaO_{4}. Phys Rev Lett 2019; 122:137201. [PMID: 31012603 DOI: 10.1103/physrevlett.122.137201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 05/02/2023]
Abstract
dc-magnetization data measured down to 40 mK speak against conventional freezing and reinstate YbMgGaO_{4} as a triangular spin-liquid candidate. Magnetic susceptibility measured parallel and perpendicular to the c axis reaches constant values below 0.1 and 0.2 K, respectively, thus indicating the presence of gapless low-energy spin excitations. We elucidate their nature in the triple-axis inelastic neutron scattering experiment that pinpoints the low-energy (E≤J_{0}∼0.2 meV) part of the excitation continuum present at low temperatures (T<J_{0}/k_{B}), but completely disappearing upon warming the system above T≫J_{0}/k_{B}. In contrast to the high-energy part at E>J_{0} that is rooted in the breaking of nearest-neighbor valence bonds and persists to temperatures well above J_{0}/k_{B}, the low-energy one originates from the rearrangement of the valence bonds and thus from the propagation of unpaired spins. We further extend this picture to herbertsmithite, the spin-liquid candidate on the kagome lattice, and argue that such a hierarchy of magnetic excitations may be a universal feature of quantum spin liquids.
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Affiliation(s)
- Yuesheng Li
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - Sebastian Bachus
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - Benqiong Liu
- Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900, People's Republic of China
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Igor Radelytskyi
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Alexandre Bertin
- Institut fuer Festkörperphysik, TU Dresden, D-01062, Dresden, Germany
| | - Astrid Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Yoshifumi Tokiwa
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - Alexander A Tsirlin
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - Philipp Gegenwart
- Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
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14
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Abstract
Nearly a century of research has established the Born-Oppenheimer approximation as a cornerstone of condensed-matter systems, stating that the motion of the atomic nuclei and electrons may be treated separately. Interactions beyond the Born-Oppenheimer approximation are at the heart of magneto-elastic functionalities and instabilities. We report comprehensive neutron spectroscopy and ab initio phonon calculations of the coupling between phonons, CEF-split localized 4f electron states, and conduction electrons in the paramagnetic regime of [Formula: see text], an archetypal Kondo lattice compound. We identify two distinct magneto-elastic hybrid excitations that form even though all coupling constants are small. First, we find a CEF-phonon bound state reminiscent of the vibronic bound state (VBS) observed in other materials. However, in contrast to an abundance of optical phonons, so far believed to be essential for a VBS, the VBS in [Formula: see text] arises from a comparatively low density of states of acoustic phonons. Second, we find a pronounced anticrossing of the CEF excitations with acoustic phonons at zero magnetic field not observed before. Remarkably, both magneto-elastic excitations are well developed despite considerable damping of the CEFs that arises dominantly by the conduction electrons. Taking together the weak coupling with the simultaneous existence of a distinct VBS and anticrossing in the same material in the presence of damping suggests strongly that similarly well-developed magneto-elastic hybrid excitations must be abundant in a wide range of materials. In turn, our study of the excitation spectra of [Formula: see text] identifies a tractable point of reference in the search for magneto-elastic functionalities and instabilities.
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Affiliation(s)
- Petr Čermák
- Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University, 121 16 Praha, Czech Republic;
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, 85748 Garching, Germany
| | - Astrid Schneidewind
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, 85748 Garching, Germany
| | - Benqiong Liu
- Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, People's Republic of China
| | | | - Christian Franz
- Heinz Maier-Leibnitz Zentrum, Technische Universität München, 85748 Garching, Germany
- Physik-Department, Technische Universität München, 85748 Garching, Germany
| | - Rudolf Schönmann
- Physik-Department, Technische Universität München, 85748 Garching, Germany
| | - Oleg Sobolev
- Institute for Physical Chemistry, Georg-August-University of Göttingen, D-37077 Göttingen, Germany
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15
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Zhang W, Wei Y, Xie T, Liu Z, Gong D, Ma X, Hu D, Čermák P, Schneidewind A, Tucker G, Meng S, Huesges Z, Lu Z, Song J, Luo W, Xu L, Zhu Z, Yin X, Li HF, Yang YF, Luo H, Li S. Unconventional Antiferromagnetic Quantum Critical Point in Ba(Fe_{0.97}Cr_{0.03})_{2}(As_{1-x}P_{x})_{2}. Phys Rev Lett 2019; 122:037001. [PMID: 30735415 DOI: 10.1103/physrevlett.122.037001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 10/04/2018] [Indexed: 06/09/2023]
Abstract
We have systematically studied physical properties of Ba(Fe_{0.97}Cr_{0.03})_{2}(As_{1-x}P_{x})_{2}, where superconductivity in BaFe_{2}(As_{1-x}P_{x})_{2} is fully suppressed by just 3% of Cr substitution of Fe. A quantum critical point is revealed at x∼0.42, where non-Fermi-liquid behaviors similar to those in BaFe_{2}(As_{1-x}P_{x})_{2} are observed. Neutron diffraction and inelastic neutron scattering measurements suggest that the quantum critical point is associated with the antiferromagnetic order, which is not of conventional spin-density-wave type as evidenced by the ω/T scaling of spin excitations. On the other hand, no divergence of low-temperature nematic susceptibility is observed when x is decreased to 0.42 from higher doping level, demonstrating that there are no nematic quantum critical fluctuations. Our results suggest that non-Fermi-liquid behaviors in iron-based superconductors can be solely resulted from the antiferromagnetic quantum critical fluctuations, which cast doubts on the role of nematic fluctuations played in the normal-state properties in iron-based superconductors.
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Affiliation(s)
- Wenliang Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yuan Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Tao Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Zhaoyu Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Dongliang Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoyan Ma
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Ding Hu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Petr Čermák
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenbergstrasse 1, 85748 Garching, Germany
- Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16, Praha, Czech Republic
| | - Astrid Schneidewind
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Gregory Tucker
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Siqin Meng
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin, Germany
- China Institute of Atomic Energy, Beijing 102413, China
| | - Zita Huesges
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin, Germany
| | - Zhilun Lu
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin, Germany
| | - Jianming Song
- Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, China
| | - Wei Luo
- Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, China
| | - Liangcai Xu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zengwei Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xunqing Yin
- Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, 999078 Macau, China
| | - Hai-Feng Li
- Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, 999078 Macau, China
| | - Yi-Feng Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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16
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Liu BQ, Park SH, Čermák P, Schneidewind A, Xiao Y. Theoretical spin-wave dispersions in the antiferromagnetic phase AF1 of MnWO 4 based on the polar atomistic model in P2. J Phys Condens Matter 2018; 30:295401. [PMID: 29869995 DOI: 10.1088/1361-648x/aaca67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The spin wave dispersions of the low temperature antiferromagnetic phase (AF1) MnWO4 have been numerically calculated based on the recently reported non-collinear spin configuration with two different canting angles. A Heisenberg model with competing magnetic exchange couplings and single-ion anisotropy terms could properly describe the spin wave excitations, including the newly observed low-lying energy excitation mode [Formula: see text] meV appearing at the magnetic zone centre. The spin wave dispersion and intensities are highly sensitive to two differently aligned spin-canting sublattices in the AF1 model. Thus this study reinsures the otherwise hardly provable hidden polar character in MnWO4.
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Affiliation(s)
- B-Q Liu
- Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900, People's Republic of China. Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, 85748 Garching, Germany
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17
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Park SH, Liu BQ, Behal D, Pedersen B, Schneidewind A. Two spin-canting textures in the antiferromagnetic phase AF1 of MnWO 4 based on the new polar atomistic model in P2. J Phys Condens Matter 2018; 30:135802. [PMID: 29498355 DOI: 10.1088/1361-648x/aaaeae] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The low temperature antiferromagnetic (AF) phase of MnWO4 (the so-called AF1 phase) exhibits different spin-canting configurations at two Mn2+ sublattices of the (3 + 1)-dimensional magnetic structure. The suggested superspace group [Formula: see text] is a significant consequence of the polar space group [Formula: see text]2 true for the nuclear structure of MnWO4. Density functional theory calculations showed that its ground state prefers this two spin-canting system. The structural difference between two independent atomic sites for Mn (Mn a , Mn b ) is too small to allow microscopically detectable electric polarisation. However, this hidden intrinsic polar character allows AF1 two commensurately modulated spin-canting textures. This is considered as the prerequisite onset of the improper ferroelectricity enhanced by the helical spin order in the multiferroic phase AF2 of MnWO4.
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Affiliation(s)
- S-H Park
- Department for Earth and Environmental Sciences, Section Crystallography, Ludwig-Maximilians-Universität München, Theresienstrasse 41, 80333 Munich, Germany
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18
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Ma Z, Wang J, Dong ZY, Zhang J, Li S, Zheng SH, Yu Y, Wang W, Che L, Ran K, Bao S, Cai Z, Čermák P, Schneidewind A, Yano S, Gardner JS, Lu X, Yu SL, Liu JM, Li S, Li JX, Wen J. Spin-Glass Ground State in a Triangular-Lattice Compound YbZnGaO_{4}. Phys Rev Lett 2018. [PMID: 29543015 DOI: 10.1103/physrevlett.120.087201] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We report on comprehensive results identifying the ground state of a triangular-lattice structured YbZnGaO_{4} as a spin glass, including no long-range magnetic order, prominent broad excitation continua, and the absence of magnetic thermal conductivity. More crucially, from the ultralow-temperature ac susceptibility measurements, we unambiguously observe frequency-dependent peaks around 0.1 K, indicating the spin-glass ground state. We suggest this conclusion holds also for its sister compound YbMgGaO_{4}, which is confirmed by the observation of spin freezing at low temperatures. We consider disorder and frustration to be the main driving force for the spin-glass phase.
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Affiliation(s)
- Zhen Ma
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jinghui Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Zhao-Yang Dong
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jun Zhang
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
| | - Shichao Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Shu-Han Zheng
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Yunjie Yu
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
| | - Wei Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Liqiang Che
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
| | - Kejing Ran
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Song Bao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Zhengwei Cai
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - P Čermák
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany
| | - A Schneidewind
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany
| | - S Yano
- National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan
| | - J S Gardner
- National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Xin Lu
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shun-Li Yu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jun-Ming Liu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shiyan Li
- State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jian-Xin Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jinsheng Wen
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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19
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Mazzone DG, Raymond S, Gavilano JL, Steffens P, Schneidewind A, Lapertot G, Kenzelmann M. Spin Resonance and Magnetic Order in an Unconventional Superconductor. Phys Rev Lett 2017; 119:187002. [PMID: 29219605 DOI: 10.1103/physrevlett.119.187002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Indexed: 06/07/2023]
Abstract
Unconventional superconductivity in many materials is believed to be mediated by magnetic fluctuations. It is an open question how magnetic order can emerge from a superconducting condensate and how it competes with the magnetic spin resonance in unconventional superconductors. Here we study a model d-wave superconductor that develops spin-density wave order, and find that the spin resonance is unaffected by the onset of static magnetic order. This result suggests a scenario, in which the resonance in Nd_{0.05}Ce_{0.95}CoIn_{5} is a longitudinal mode with fluctuating moments along the ordered magnetic moments.
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Affiliation(s)
- D G Mazzone
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - S Raymond
- Univ. Grenoble Alpes and CEA, INAC, MEM, F-38000 Grenoble, France
| | - J L Gavilano
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - P Steffens
- Institut Laue-Langevin, 38042 Grenoble, France
| | - A Schneidewind
- Jülich Center for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
| | - G Lapertot
- Univ. Grenoble Alpes and CEA, INAC, PHELIQS, F-38000 Grenoble, France
| | - M Kenzelmann
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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20
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Christ JBM, Tannapfel A, Kukuk G, Schlottmann K, Straßburg C, Schneidewind A. [A 59-year-old woman with upper abdominal pain and fever]. Internist (Berl) 2017; 58:1090-1096. [PMID: 28555378 DOI: 10.1007/s00108-017-0255-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
A 59-year-old woman suffered from fever and upper abdominal pain. The computed tomography (CT) scan revealed a liver lesion. Conventional imaging techniques (CT, magnetic resonance imaging, contrast-enhanced ultrasonography) did not allow for a consistent diagnosis. Fine needle biopsy of the liver lesion was performed. Histologically, fibrotic inflammation was found and an inflammatory pseudotumor (IPT) diagnosed. Despite treatment with steroids and antibiotics, the size of the IPT increased; thus, surgical resection was necessary. In case of fever of unknown origin, IPT should be considered as a potential diagnosis.
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Affiliation(s)
- J B M Christ
- Klinik für Gastroenterologie, Diabetologie und Innere Medizin, Krankenhaus Porz am Rhein gGmbH, Urbacher Weg 19, 51149, Köln, Deutschland.
| | - A Tannapfel
- Institut für Pathologie, Universität Bochum, Bochum, Deutschland
| | - G Kukuk
- Radiologische Klinik, Universitätsklinikum Bonn, Bonn, Deutschland
| | - K Schlottmann
- Klinik für Gastroenterologie, Katharinen-Hospital Unna, Unna, Deutschland
| | - C Straßburg
- Medizinische Klinik und Poliklinik I, Universitätsklinikum Bonn, Bonn, Deutschland
| | - A Schneidewind
- Medizinische Klinik und Poliklinik I, Universitätsklinikum Bonn, Bonn, Deutschland
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21
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Hamann A, Stockert O, Fritsch V, Grube K, Schneidewind A, Löhneysen HV. Evolution of the magnetic structure in CeCu(5.5)Au(0.5) under pressure towards quantum criticality. Phys Rev Lett 2013; 110:096404. [PMID: 23496732 DOI: 10.1103/physrevlett.110.096404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Indexed: 06/01/2023]
Abstract
In the prototypical heavy-fermion system CeCu(6-x)Au(x), a magnetic quantum critical point can be tuned by Au concentration x, hydrostatic pressure p, or magnetic field B. A striking equivalence of the tuning behavior with x or p had been found with respect to thermodynamic and transport properties. By means of elastic neutron scattering on single crystalline CeCu(5.5)Au(0.5), we demonstrate this x-p equivalence on a microscopic level by showing that the magnetic ordering wave vector q(m) can be tuned accordingly. At ambient pressure,CeCu(5.5)Au(0.5) orders at q(m)≈(0.59 0 0). Upon applying p=4.1 kbar, q(m)≈(0.61 0 0.21) is found corresponding to CeCu(5.6)Au(0.4) at ambient pressure. The transition seems to occur in a first-order fashion and to be governed by slight changes in the nesting properties of the Fermi surface.
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Affiliation(s)
- A Hamann
- Institut für Festkörperphysik, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany
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22
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Mourigal M, Enderle M, Fåk B, Kremer RK, Law JM, Schneidewind A, Hiess A, Prokofiev A. Evidence of a bond-nematic phase in LiCuVO4. Phys Rev Lett 2012; 109:027203. [PMID: 23030203 DOI: 10.1103/physrevlett.109.027203] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Indexed: 06/01/2023]
Abstract
Polarized and unpolarized neutron scattering experiments on the frustrated ferromagnetic spin-1/2 chain LiCuVO4 show that the phase transition at H(Q) of 8 T is driven by quadrupolar fluctuations and that dipolar correlations are short range with moments parallel to the applied magnetic field in the high-field phase. Heat-capacity measurements evidence a phase transition into this high-field phase, with an anomaly clearly different from that at low magnetic fields. Our experimental data are consistent with a picture where the ground state above H(Q) has a next-nearest neighbor bond-nematic order along the chains with a fluidlike coherence between weakly coupled chains.
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Affiliation(s)
- M Mourigal
- Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9, France
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23
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Li S, Zhang C, Wang M, Luo HQ, Lu X, Faulhaber E, Schneidewind A, Link P, Hu J, Xiang T, Dai P. Normal-state hourglass dispersion of the spin excitations in FeSexTe(1-x). Phys Rev Lett 2010; 105:157002. [PMID: 21230929 DOI: 10.1103/physrevlett.105.157002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Revised: 07/13/2010] [Indexed: 05/30/2023]
Abstract
We use cold neutron spectroscopy to study the low-energy spin excitations of superconducting (SC) FeSe0.4Te0.6 and essentially nonsuperconducting (NSC) FeSe0.45Te0.55. In contrast with BaFe2-x(Co,Ni)xAs2, where the low-energy spin excitations are commensurate both in the SC and normal state, the normal-state spin excitations in SC FeSe0.4Te0.6 are incommensurate and show an hourglass dispersion near the resonance energy. Since similar hourglass dispersion is also found in the NSC FeSe0.45Te0.55, we argue that the observed incommensurate spin excitations in FeSe(1-x)Tex are not directly associated with superconductivity. Instead, the results can be understood within a picture of Fermi surface nesting assuming extremely low Fermi velocities and spin-orbital coupling.
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Affiliation(s)
- Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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24
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Doert T, Schneidewind A, Hölzel M, Rutzinger D, Ruck M. The magnetic structure of CeAgAs 2. Acta Crystallogr A 2010. [DOI: 10.1107/s0108767310097795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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25
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Oniangue-Ndza C, Schneidewind A, Brockman MA, Brumme ZL, Boutwell CL, Wang YE, Brumme CJ, Power KA, Gladden AD, Kemper M, Le Gall S, Streeck H, Alter G, Altfeld M, Heckerman D, Walker BD, Allen TM. P09-10. Impact of CTL escape mutations in HIV-1 Nef on viral replication. Retrovirology 2009. [PMCID: PMC2767608 DOI: 10.1186/1742-4690-6-s3-p123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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26
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Boutwell CL, Schneidewind A, Brumme Z, Brockman M, Streeck H, Brumme C, Dudek T, Kane K, Kemper M, Walker B, Altfeld M, Allen T. P09-19 LB. CTL escape mutations in gag epitopes restricted by protective HLA class I alleles cause substantial reductions in viral replication capacity. Retrovirology 2009. [PMCID: PMC2767913 DOI: 10.1186/1742-4690-6-s3-p399] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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27
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Koegl C, Wolf E, Hanhoff N, Jessen H, Schewe K, Rausch M, Goelz J, Goetzenich A, Knechten H, Jaeger H, Becker W, Becker-Boost I, Berzow D, Beiniek B, Brust J, Shcuster D, Dupke S, Fenske S, Gellermann HJ, Gippert R, Hartmann P, Hintsche B, Jaeger H, Jaegel-Guedes E, Jessen H, Gölz J, Koelzsch J, Helm EB, Knecht G, Knechten H, Lochet I, Gute P, Mauruschat S, Mauss S, Miasnikov V, Mosthaf FA, Rausch M, Freiwald M, Reuter B, Schalk HM, Schappert B, Schnaitmann E, Schneider I, Schüler-Maué W, Schuler C, Seidel T, Starke W, Ulmer A, Müller M, Weitner I, Schewe K, Zamani C, Hanmond A, Ross K, Bottlaender A, Hoffmann C, Dix A, Schneidewind A, Lademann M. Treatment during primary HIV infection does not lower viral set point but improves CD4 lymphocytes in an observational cohort. Eur J Med Res 2009; 14:277-83. [PMID: 19661009 PMCID: PMC3458637 DOI: 10.1186/2047-783x-14-7-277] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Objective To investigate if early treatment of primary HIV-1 infection (PHI) reduces viral set point and/or increases CD4 lymphocytes. Methods Analysis of two prospective multi-centre PHI cohorts. HIV-1 RNA and CD4 lymphocytes in patients with transient treatment were compared to those in untreated patients. Time to CD4 lymphocyte decrease below 350/μl after treatment stop or seroconversion was calculated using Kaplan-Meier and Cox-PH-regression analyses. Results 156 cases of PHI were included, of which 100 had received transient HAART (median treatment time 9.5 months) and 56 remained untreated. Median viral load (563000 cop/ml vs 240000 cop/ml; p < 0.001) and median CD4 lymphocyte (449/μl vs. 613/μl; p < 0.01) differed significantly between treated and untreated patients. Median viral load was 38056 copies/ml in treated patients (12 months after treatment stop) and 52880 copies/ml in untreated patients (12 months after seroconversion; ns). Median CD4 lymphocyte change was +60/μl vs. -86/μl (p = 0.01). Median time until CD4 lymphocytes decreased to < 350/μl (including all patients with CD4 lymphocytes < 500/μl during seroconversion) was 20.7 months in treated patients after treatment stop and 8.3 months in untreated patents after seroconversion (p < 0.01). Cox-PH analyses adjusting for baseline VL, CD4 lymphocytes, stage of early infection and symptoms confirmed these differences. Conclusions Treatment during PHI did not lower viral set point. However, patients treated during seroconversion had an increase in CD4 lymphocytes, whereas untreated patients experienced a decrease in CD4 lymphocytes. Time until reaching CD4 lymphocytes < 350/μl was significantly shorter in untreated than in treated patients including patients with CD4 lymphocytes < 500/μl during seroconversion.
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Affiliation(s)
- C Koegl
- MUC Research, Karlsplatz 8, 80335 Munich, Germany.
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28
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Harriger LW, Schneidewind A, Li S, Zhao J, Li Z, Lu W, Dong X, Zhou F, Zhao Z, Hu J, Dai P. Transition from three-dimensional anisotropic spin excitations to two-dimensional spin excitations by electron doping the FeAs-based BaFe1.96Ni0.04As2 superconductor. Phys Rev Lett 2009; 103:087005. [PMID: 19792752 DOI: 10.1103/physrevlett.103.087005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Indexed: 05/28/2023]
Abstract
We use neutron scattering to study the effect of electron doping on the structural or magnetic order in BaFe2As2. In the undoped state, BaFe2As2 exhibits simultaneous structural and magnetic phase transitions below 143 K. Upon electron doping to form BaFe1.96Ni0.04As2, the system first displays the lattice distortion near approximately 97 K, and then orders antiferromagnetically at 91 K before developing weak superconductivity below approximately 15 K. The effect of electron doping is to reduce the c-axis exchange coupling in BaFe2As2 and induce quasi-two-dimensional (2D) spin excitations. These results suggest that the transition from 3D spin waves to quasi-2D spin excitations by electron doping is important for the separated structural and magnetic phase transitions in iron arsenides.
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Affiliation(s)
- Leland W Harriger
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
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29
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Tsyrulin N, Pardini T, Singh RRP, Xiao F, Link P, Schneidewind A, Hiess A, Landee CP, Turnbull MM, Kenzelmann M. Quantum effects in a weakly frustrated s=1/2 two-dimensional heisenberg antiferromagnet in an applied magnetic field. Phys Rev Lett 2009; 102:197201. [PMID: 19518991 DOI: 10.1103/physrevlett.102.197201] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Indexed: 05/27/2023]
Abstract
We have studied the two-dimensional S=1/2 square-lattice antiferromagnet Cu(pz)_{2}(ClO4)_{2} (where pz denotes pyrazine), using neutron inelastic scattering and series expansion calculations. We show that the presence of antiferromagnetic next-nearest-neighbor interactions enhances quantum fluctuations associated with resonating valence bonds. Intermediate magnetic fields lead to a selective tuning of resonating valence bonds and a spectacular inversion of the zone-boundary dispersion, providing novel insight into 2D antiferromagnetism in the quantum limit.
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Affiliation(s)
- N Tsyrulin
- Laboratory for Solid State Physics, ETH Zurich, CH-8093 Zurich, Switzerland
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30
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Chang J, Christensen NB, Niedermayer C, Lefmann K, Rønnow HM, McMorrow DF, Schneidewind A, Link P, Hiess A, Boehm M, Mottl R, Pailhés S, Momono N, Oda M, Ido M, Mesot J. Magnetic-field-induced soft-mode quantum phase transition in the high-temperature superconductor La1.855Sr0.145CuO4: an inelastic neutron-scattering study. Phys Rev Lett 2009; 102:177006. [PMID: 19518819 DOI: 10.1103/physrevlett.102.177006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Indexed: 05/27/2023]
Abstract
Inelastic neutron-scattering experiments on the high-temperature superconductor La1.855Sr0.145CuO4 reveal a magnetic excitation gap Delta that decreases continuously upon application of a magnetic field perpendicular to the CuO2 planes. The gap vanishes at the critical field required to induce long-range incommensurate antiferromagnetic order, providing compelling evidence for a field-induced soft-mode driven quantum phase transition.
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Affiliation(s)
- J Chang
- Laboratory for Neutron Scattering, ETH Zurich and PSI Villigen, CH-5232 Villigen PSI, Switzerland.
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31
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Chi S, Schneidewind A, Zhao J, Harriger LW, Li L, Luo Y, Cao G, Xu Z, Loewenhaupt M, Hu J, Dai P. Inelastic neutron-scattering measurements of a three-dimensional spin resonance in the FeAs-based BaFe1.9Ni0.1As2 superconductor. Phys Rev Lett 2009; 102:107006. [PMID: 19392150 DOI: 10.1103/physrevlett.102.107006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Indexed: 05/27/2023]
Abstract
We use inelastic neutron scattering to study magnetic excitations of the FeAs-based superconductor BaFe1.9Ni0.1As2 above and below its T_{c} (=20 K). In addition to gradually open a spin gap at the in-plane antiferromagnetic ordering wave vector (1, 0, 0), the effect of superconductivity is to form a three-dimensional resonance with clear dispersion along the c axis. The intensity of the resonance develops like a superconducting order parameter, and the mode occurs at distinctively different energies at (1, 0, 0) and (1, 0, 1). If the resonance energy is associated with the superconducting gap energy Delta, then Delta is dependent on the wave vector transfers along the c axis. These results suggest that one must be careful in interpreting the superconducting gap energies obtained by surface sensitive probes such as scanning tunneling microscopy and angle resolved photoemission.
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Affiliation(s)
- Songxue Chi
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA
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32
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Tsyrulin N, Kenzelmann M, Xiao F, Link P, Schneidewind A, Hiess A, Landee C, Turnbull M. Quantum effects in S= 1/2 two-dimensional Heisenberg antiferromagnet in applied magnetic field. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308086686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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33
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Schneidewind A, Link P, Etzdorf D, Stockert O, Loewenhaupt M. Scientific Review: PANDA: The Cold Three-Axis Spectrometer at FRM II. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/10448630701623087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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34
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Rieder F, Schneidewind A, Bolder U, Zorger N, Schölmerich J, Schäffler A, Gölder S, Kullmann F, Herfarth H. Use of anticoagulation during wireless capsule endoscopy for the investigation of recurrent obscure gastrointestinal bleeding. Endoscopy 2006; 38:526-8. [PMID: 16767592 DOI: 10.1055/s-2006-925002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Detecting the source of obscure gastrointestinal bleeding can be difficult. Capsule endoscopy is a promising diagnostic tool for investigating patients with this condition, although identifying the source of intermittent or low-grade bleeding remains a diagnostic challenge. We present case reports of two patients with obscure gastrointestinal bleeding, in whom the source of recurrent bleeding episodes was diagnosed by capsule endoscopy while they were on anticoagulation therapy. The first patient, an 81-year-old white woman, was on long-term oral anticoagulation because she had chronic atrial fibrillation. Capsule endoscopy demonstrated a bleeding tumor in the region of the terminal ileum. The second patient, a 59-year-old white man, underwent an initial capsule endoscopy, which was negative. After initiation of anticoagulation with heparin, a second capsule endoscopy procedure in this patient revealed several small bleeding lesions in the proximal small bowel. In both cases a gastrointestinal stromal tumor was identified as the bleeding source and was resected. These two cases demonstrate that provocation of bleeding during capsule endoscopy may increase its sensitivity.
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Affiliation(s)
- F Rieder
- Department of Internal Medicine I, University of Regensburg, Regensburg, Germany.
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35
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Schneidewind A, Kreyssig A, Loewenhaupt M. Magnetic X-ray scattering and the example of the investigation ofRCu2 compounds (R = rare earth). Cryst Res Technol 2005. [DOI: 10.1002/crat.200410319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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36
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Schneidewind A. [A therapeutic approach in Burkitt's lymphoma. 2 case reports from the Hospital Central da Beira/Mozambique]. Fortschr Med Orig 2002; 119:5-8. [PMID: 11935660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Burkitt's lymphoma is the most common malignant tumor encountered in children (age peak 3 to 8 years) living in areas with endemic malaria tropica. In the Hospital Central da Beira/Mozambique, two children with Burkitt's lymphoma were treated with cyclophosphamide. During the period covered by this report--August 1 to September 30, 2000--two of the required four treatment cycles were carried out, and both children experienced a remission.
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37
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Wissenbach U, Niemeyer BA, Fixemer T, Schneidewind A, Trost C, Cavalie A, Reus K, Meese E, Bonkhoff H, Flockerzi V. Expression of CaT-like, a novel calcium-selective channel, correlates with the malignancy of prostate cancer. J Biol Chem 2001; 276:19461-8. [PMID: 11278579 DOI: 10.1074/jbc.m009895200] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The regulation of intracellular Ca(2+) plays a key role in the development and growth of cells. Here we report the cloning and functional expression of a highly calcium-selective channel localized on the human chromosome 7. The sequence of the new channel is structurally related to the gene product of the CaT1 protein cloned from rat duodenum and is therefore called CaT-like (CaT-L). CaT-L is expressed in locally advanced prostate cancer, metastatic and androgen-insensitive prostatic lesions but is undetectable in healthy prostate tissue and benign prostatic hyperplasia. Additionally, CaT-L is expressed in normal placenta, exocrine pancreas, and salivary glands. New markers with well defined biological function that correlate with aberrant cell growth are needed for the molecular staging of cancer and to predict the clinical outcome. The human CaT-L channel represents a marker for prostate cancer progression and may serve as a target for therapeutic strategies.
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Affiliation(s)
- U Wissenbach
- Institut für Pharmakologie und Toxikologie, Institut für Humangnetik, und Institut für Pathologie der Universität des Saarlandes, D 66421 Homburg, Germany
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