1
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He W, Shen Y, Wohlfeld K, Sears J, Li J, Pelliciari J, Walicki M, Johnston S, Baldini E, Bisogni V, Mitrano M, Dean MPM. Magnetically propagating Hund's exciton in van der Waals antiferromagnet NiPS 3. Nat Commun 2024; 15:3496. [PMID: 38664432 PMCID: PMC11045826 DOI: 10.1038/s41467-024-47852-x] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Magnetic van der Waals (vdW) materials have opened new frontiers for realizing novel many-body phenomena. Recently NiPS3 has received intense interest since it hosts an excitonic quasiparticle whose properties appear to be intimately linked to the magnetic state of the lattice. Despite extensive studies, the electronic character, mobility, and magnetic interactions of the exciton remain unresolved. Here we address these issues by measuring NiPS3 with ultra-high energy resolution resonant inelastic x-ray scattering (RIXS). We find that Hund's exchange interactions are primarily responsible for the energy of formation of the exciton. Measuring the dispersion of the Hund's exciton reveals that it propagates in a way that is analogous to a double-magnon. We trace this unique behavior to fundamental similarities between the NiPS3 exciton hopping and spin exchange processes, underlining the unique magnetic characteristics of this novel quasiparticle.
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Affiliation(s)
- W He
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - Y Shen
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - K Wohlfeld
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Warsaw, PL-02093, Poland
| | - J Sears
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - J Li
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - J Pelliciari
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M Walicki
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Warsaw, PL-02093, Poland
| | - S Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, 37996, USA
- Institute of Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, TN, 37996, USA
| | - E Baldini
- Department of Physics, The University of Texas at Austin, Austin, TX, 78712, USA
| | - V Bisogni
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M Mitrano
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, 11973, USA.
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2
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Li XT, Tu SJ, Chaix L, Fawaz C, d'Astuto M, Li X, Yakhou-Harris F, Kummer K, Brookes NB, Garcia-Fernandez M, Zhou KJ, Lin ZF, Yuan J, Jin K, Dean MPM, Liu X. Evolution of the Magnetic Excitations in Electron-Doped La_{2-x}Ce_{x}CuO_{4}. Phys Rev Lett 2024; 132:056002. [PMID: 38364146 DOI: 10.1103/physrevlett.132.056002] [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: 06/02/2023] [Accepted: 12/12/2023] [Indexed: 02/18/2024]
Abstract
We investigated the high energy spin excitations in electron-doped La_{2-x}Ce_{x}CuO_{4}, a cuprate superconductor, by resonant inelastic x-ray scattering (RIXS) measurements. Efforts were paid to disentangle the paramagnon signal from non-spin-flip spectral weight mixing in the RIXS spectrum at Q_{∥}=(0.6π,0) and (0.9π,0) along the (1 0) direction. Our results show that, for doping level x from 0.07 to 0.185, the variation of the paramagnon excitation energy is marginal. We discuss the implication of our results in connection with the evolution of the electron correlation strength in this system.
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Affiliation(s)
- X T Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - S J Tu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - L Chaix
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - C Fawaz
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - M d'Astuto
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - X Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - F Yakhou-Harris
- European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex, France
| | - K Kummer
- European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex, France
| | - N B Brookes
- European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex, France
| | | | - Ke-Jin Zhou
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - Z F Lin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J Yuan
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - K Jin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
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3
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Fabbris G, Meyers D, Shen Y, Bisogni V, Zhang J, Mitchell JF, Norman MR, Johnston S, Feng J, Chiuzbăian GS, Nicolaou A, Jaouen N, Dean MPM. Resonant inelastic x-ray scattering data for Ruddlesden-Popper and reduced Ruddlesden-Popper nickelates. Sci Data 2023; 10:174. [PMID: 36991033 PMCID: PMC10060392 DOI: 10.1038/s41597-023-02079-1] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 03/16/2023] [Indexed: 03/31/2023] Open
Abstract
Ruddlesden-Popper and reduced Ruddlesden-Popper nickelates are intriguing candidates for mimicking the properties of high-temperature superconducting cuprates. The degree of similarity between these nickelates and cuprates has been the subject of considerable debate. Resonant inelastic x-ray scattering (RIXS) has played an important role in exploring their electronic and magnetic excitations, but these efforts have been stymied by inconsistencies between different samples and the lack of publicly available data for detailed comparison. To address this issue, we present open RIXS data on La4Ni3O10 and La4Ni3O8.
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Affiliation(s)
- G Fabbris
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA.
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois, 60439, USA.
| | - D Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Y Shen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - V Bisogni
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - J Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois, 60439, USA
- Institute of Crystal Materials, Shandong University, Jinan, Shandong, 250100, China
| | - J F Mitchell
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois, 60439, USA
| | - M R Norman
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois, 60439, USA
| | - S Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee, 37966, USA
- Institute of Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - J Feng
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, 75005, Paris, France
- Institute of Advanced Science Facilities, Shenzhen, Guangdong, 518107, China
| | - G S Chiuzbăian
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, 75005, Paris, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192, Gif-sur-Yvette, France
| | - A Nicolaou
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192, Gif-sur-Yvette, France
| | - N Jaouen
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192, Gif-sur-Yvette, France
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA.
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4
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Shen Y, Sears J, Fabbris G, Weichselbaum A, Yin W, Zhao H, Mazzone DG, Miao H, Upton MH, Casa D, Acevedo-Esteves R, Nelson C, Barbour AM, Mazzoli C, Cao G, Dean MPM. Emergence of Spinons in Layered Trimer Iridate Ba_{4}Ir_{3}O_{10}. Phys Rev Lett 2022; 129:207201. [PMID: 36461990 DOI: 10.1103/physrevlett.129.207201] [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: 01/04/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Spinons are well known as the elementary excitations of one-dimensional antiferromagnetic chains, but means to realize spinons in higher dimensions is the subject of intense research. Here, we use resonant x-ray scattering to study the layered trimer iridate Ba_{4}Ir_{3}O_{10}, which shows no magnetic order down to 0.2 K. An emergent one-dimensional spinon continuum is observed that can be well described by XXZ spin-1/2 chains with a magnetic exchange of ∼55 meV and a small Ising-like anisotropy. With 2% isovalent Sr doping, magnetic order appears below T_{N}=130 K along with sharper excitations in (Ba_{1-x}Sr_{x})_{4}Ir_{3}O_{10}. Combining our data with exact diagonalization calculations, we find that the frustrated intratrimer interactions effectively reduce the system into decoupled spin chains, the subtle balance of which can be easily tipped by perturbations such as chemical doping. Our results put Ba_{4}Ir_{3}O_{10} between the one-dimensional chain and two-dimensional quantum spin liquid scenarios, illustrating a new way to suppress magnetic order and realize fractional spinons.
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Affiliation(s)
- Y Shen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J Sears
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - A Weichselbaum
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - W Yin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - H Zhao
- Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - D G Mazzone
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - M H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - D Casa
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - R Acevedo-Esteves
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Nelson
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A M Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G Cao
- Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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5
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Li H, Zhang TT, Said A, Fabbris G, Mazzone DG, Yan JQ, Mandrus D, Halász GB, Okamoto S, Murakami S, Dean MPM, Lee HN, Miao H. Giant phonon anomalies in the proximate Kitaev quantum spin liquid α-RuCl 3. Nat Commun 2021; 12:3513. [PMID: 34112804 PMCID: PMC8192767 DOI: 10.1038/s41467-021-23826-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 04/30/2021] [Indexed: 11/18/2022] Open
Abstract
The Kitaev quantum spin liquid epitomizes an entangled topological state, for which two flavors of fractionalized low-energy excitations are predicted: the itinerant Majorana fermion and the Z2 gauge flux. It was proposed recently that fingerprints of fractional excitations are encoded in the phonon spectra of Kitaev quantum spin liquids through a novel fractional-excitation-phonon coupling. Here, we detect anomalous phonon effects in α-RuCl3 using inelastic X-ray scattering with meV resolution. At high temperature, we discover interlaced optical phonons intercepting a transverse acoustic phonon between 3 and 7 meV. Upon decreasing temperature, the optical phonons display a large intensity enhancement near the Kitaev energy, JK~8 meV, that coincides with a giant acoustic phonon softening near the Z2 gauge flux energy scale. These phonon anomalies signify the coupling of phonon and Kitaev magnetic excitations in α-RuCl3 and demonstrates a proof-of-principle method to detect anomalous excitations in topological quantum materials.
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Affiliation(s)
- Haoxiang Li
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - T T Zhang
- Department of Physics, Tokyo Institute of Technology, Okayama, Meguro-ku, Tokyo, Japan
- Tokodai Institute for Element Strategy, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagawa, Japan
| | - A Said
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - D G Mazzone
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, USA
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Villigen, Switzerland
| | - J Q Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - D Mandrus
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Materials Science and Engineering, the University of Tennessee at Knoxville, Knoxville, TN, USA
| | - Gábor B Halász
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - S Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - S Murakami
- Department of Physics, Tokyo Institute of Technology, Okayama, Meguro-ku, Tokyo, Japan
- Tokodai Institute for Element Strategy, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagawa, Japan
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, USA
| | - H N Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - H Miao
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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6
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Shen Y, Fabbris G, Miao H, Cao Y, Meyers D, Mazzone DG, Assefa TA, Chen XM, Kisslinger K, Prabhakaran D, Boothroyd AT, Tranquada JM, Hu W, Barbour AM, Wilkins SB, Mazzoli C, Robinson IK, Dean MPM. Charge Condensation and Lattice Coupling Drives Stripe Formation in Nickelates. Phys Rev Lett 2021; 126:177601. [PMID: 33988428 DOI: 10.1103/physrevlett.126.177601] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
Revealing the predominant driving force behind symmetry breaking in correlated materials is sometimes a formidable task due to the intertwined nature of different degrees of freedom. This is the case for La_{2-x}Sr_{x}NiO_{4+δ}, in which coupled incommensurate charge and spin stripes form at low temperatures. Here, we use resonant x-ray photon correlation spectroscopy to study the temporal stability and domain memory of the charge and spin stripes in La_{2-x}Sr_{x}NiO_{4+δ}. Although spin stripes are more spatially correlated, charge stripes maintain a better temporal stability against temperature change. More intriguingly, charge order shows robust domain memory with thermal cycling up to 250 K, far above the ordering temperature. These results demonstrate the pinning of charge stripes to the lattice and that charge condensation is the predominant factor in the formation of stripe orders in nickelates.
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Affiliation(s)
- Y Shen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G Fabbris
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Y Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - D Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA
| | - D G Mazzone
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - T A Assefa
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X M Chen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - K Kisslinger
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - D Prabhakaran
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, United Kingdom
| | - A T Boothroyd
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, United Kingdom
| | - J M Tranquada
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - W Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A M Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - S B Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - I K Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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7
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Lin JQ, Villar Arribi P, Fabbris G, Botana AS, Meyers D, Miao H, Shen Y, Mazzone DG, Feng J, Chiuzbăian SG, Nag A, Walters AC, García-Fernández M, Zhou KJ, Pelliciari J, Jarrige I, Freeland JW, Zhang J, Mitchell JF, Bisogni V, Liu X, Norman MR, Dean MPM. Strong Superexchange in a d^{9-δ} Nickelate Revealed by Resonant Inelastic X-Ray Scattering. Phys Rev Lett 2021; 126:087001. [PMID: 33709756 DOI: 10.1103/physrevlett.126.087001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
The discovery of superconductivity in a d^{9-δ} nickelate has inspired disparate theoretical perspectives regarding the essential physics of this class of materials. A key issue is the magnitude of the magnetic superexchange, which relates to whether cuprate-like high-temperature nickelate superconductivity could be realized. We address this question using Ni L-edge and O K-edge spectroscopy of the reduced d^{9-1/3} trilayer nickelates R_{4}Ni_{3}O_{8} (where R=La, Pr) and associated theoretical modeling. A magnon energy scale of ∼80 meV resulting from a nearest-neighbor magnetic exchange of J=69(4) meV is observed, proving that d^{9-δ} nickelates can host a large superexchange. This value, along with that of the Ni-O hybridization estimated from our O K-edge data, implies that trilayer nickelates represent an intermediate case between the infinite-layer nickelates and the cuprates. Layered nickelates thus provide a route to testing the relevance of superexchange to nickelate superconductivity.
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Affiliation(s)
- J Q Lin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - P Villar Arribi
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - G Fabbris
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - A S Botana
- Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
| | - D Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Y Shen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - D G Mazzone
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - J Feng
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 4 place Jussieu, 75252 Paris Cedex 05, France
| | - S G Chiuzbăian
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 4 place Jussieu, 75252 Paris Cedex 05, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - A Nag
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - A C Walters
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - M García-Fernández
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Ke-Jin Zhou
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - J Pelliciari
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - I Jarrige
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Junjie Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
- Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - J F Mitchell
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - V Bisogni
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - M R Norman
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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8
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Lin JQ, Miao H, Mazzone DG, Gu GD, Nag A, Walters AC, García-Fernández M, Barbour A, Pelliciari J, Jarrige I, Oda M, Kurosawa K, Momono N, Zhou KJ, Bisogni V, Liu X, Dean MPM. Strongly Correlated Charge Density Wave in La_{2-x}Sr_{x}CuO_{4} Evidenced by Doping-Dependent Phonon Anomaly. Phys Rev Lett 2020; 124:207005. [PMID: 32501068 DOI: 10.1103/physrevlett.124.207005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
The discovery of charge-density-wave-related effects in the resonant inelastic x-ray scattering spectra of cuprates holds the tantalizing promise of clarifying the interactions that stabilize the electronic order. Here, we report a comprehensive resonant inelastic x-ray scattering study of La_{2-x}Sr_{x}CuO_{4} finding that charge-density wave effects persist up to a remarkably high doping level of x=0.21 before disappearing at x=0.25. The inelastic excitation spectra remain essentially unchanged with doping despite crossing a topological transition in the Fermi surface. This indicates that the spectra contain little or no direct coupling to electronic excitations near the Fermi surface, rather they are dominated by the resonant cross section for phonons and charge-density-wave-induced phonon softening. We interpret our results in terms of a charge-density wave that is generated by strong correlations and a phonon response that is driven by the charge-density-wave-induced modification of the lattice.
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Affiliation(s)
- J Q Lin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - D G Mazzone
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G D Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A Nag
- Diamond Light Source, Harwell Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - A C Walters
- Diamond Light Source, Harwell Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - M García-Fernández
- Diamond Light Source, Harwell Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - A Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J Pelliciari
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - I Jarrige
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - M Oda
- Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
| | - K Kurosawa
- Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
| | - N Momono
- Department of Sciences and Informatics, Muroran Institute of Technology, Muroran 050-8585, Japan
| | - Ke-Jin Zhou
- Diamond Light Source, Harwell Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - V Bisogni
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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9
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Zhang TT, Miao H, Wang Q, Lin JQ, Cao Y, Fabbris G, Said AH, Liu X, Lei HC, Fang Z, Weng HM, Dean MPM. Phononic Helical Nodal Lines with PT Protection in MoB_{2}. Phys Rev Lett 2019; 123:245302. [PMID: 31922848 DOI: 10.1103/physrevlett.123.245302] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Indexed: 06/10/2023]
Abstract
While condensed matter systems host both fermionic and bosonic quasiparticles, reliably predicting and empirically verifying topological states is only mature for Fermionic electronic structures, leaving topological Bosonic excitations sporadically explored. This is unfortunate, as Bosonic systems such as phonons offer the opportunity to assess spinless band structures where nodal lines can be realized without invoking special additional symetries to protect against spin-orbit coupling. Here we combine first-principles calculations and meV-resolution inelastic x-ray scattering to demonstrate the first realization of parity-time reversal symmetry protected helical nodal lines in the phonon spectrum of MoB_{2}. This structure is unique to phononic systems as the spin-orbit coupling present in electronic systems tends to lift the degeneracy away from high-symmetry locations. Our study establishes a protocol to accurately identify topological Bosonic excitations, opening a new route to explore exotic topological states in crystalline materials.
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Affiliation(s)
- T T Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Department of Physics, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan
- Tokodai Institute for Element Strategy, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Q Wang
- Department of Physics and Beijing Key Laboratory of Opto-Electronic Functional Materials and Micro-devices, Renmin University of China, Beijing, China
| | - J Q Lin
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Y Cao
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - A H Said
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - X Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - H C Lei
- Department of Physics and Beijing Key Laboratory of Opto-Electronic Functional Materials and Micro-devices, Renmin University of China, Beijing, China
| | - Z Fang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - H M Weng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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10
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Hao L, Wang Z, Yang J, Meyers D, Sanchez J, Fabbris G, Choi Y, Kim JW, Haskel D, Ryan PJ, Barros K, Chu JH, Dean MPM, Batista CD, Liu J. Anomalous magnetoresistance due to longitudinal spin fluctuations in a J eff = 1/2 Mott semiconductor. Nat Commun 2019; 10:5301. [PMID: 31757946 PMCID: PMC6874576 DOI: 10.1038/s41467-019-13271-6] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 10/24/2019] [Indexed: 11/09/2022] Open
Abstract
As a hallmark of electronic correlation, spin-charge interplay underlies many emergent phenomena in doped Mott insulators, such as high-temperature superconductivity, whereas the half-filled parent state is usually electronically frozen with an antiferromagnetic order that resists external control. We report on the observation of a positive magnetoresistance that probes the staggered susceptibility of a pseudospin-half square-lattice Mott insulator built as an artificial SrIrO3/SrTiO3 superlattice. Its size is particularly large in the high-temperature insulating paramagnetic phase near the Néel transition. This magnetoresistance originates from a collective charge response to the large longitudinal spin fluctuations under a linear coupling between the external magnetic field and the staggered magnetization enabled by strong spin-orbit interaction. Our results demonstrate a magnetic control of the binding energy of the fluctuating particle-hole pairs in the Slater-Mott crossover regime analogous to the Bardeen-Cooper-Schrieffer-to-Bose-Einstein condensation crossover of ultracold-superfluids. Spin-charge interactions are at the core of electronic correlation phenomena in Mott insulators. Here, the authors observe a positive anomalous magnetoresistance in a SrIrO3/SrTiO3 superlattice, indicative of strong spin-charge fluctuations in this pseudospin-half square-lattice Mott insulator.
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Affiliation(s)
- Lin Hao
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
| | - Zhentao Wang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
| | - Junyi Yang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
| | - D Meyers
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Joshua Sanchez
- Department of Physics, University of Washington, Seattle, WA, 98105, USA
| | - Gilberto Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Daniel Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Philip J Ryan
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA.,School of Physical Sciences, Dublin City University, Dublin 9, Ireland
| | - Kipton Barros
- Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, WA, 98105, USA
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Cristian D Batista
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.,Quantum Condensed Matter Division and Shull-Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.
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11
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Cao Y, Mazzone DG, Meyers D, Hill JP, Liu X, Wall S, Dean MPM. Ultrafast dynamics of spin and orbital correlations in quantum materials: an energy- and momentum-resolved perspective. Philos Trans A Math Phys Eng Sci 2019; 377:20170480. [PMID: 30929631 PMCID: PMC6452052 DOI: 10.1098/rsta.2017.0480] [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] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/31/2018] [Indexed: 05/07/2023]
Abstract
Many remarkable properties of quantum materials emerge from states with intricate coupling between the charge, spin and orbital degrees of freedom. Ultrafast photo-excitation of these materials holds great promise for understanding and controlling the properties of these states. Here, we introduce time-resolved resonant inelastic X-ray scattering (tr-RIXS) as a means of measuring the charge, spin and orbital excitations out of equilibrium. These excitations encode the correlations and interactions that determine the detailed properties of the states generated. After outlining the basic principles and instrumentations of tr-RIXS, we review our first observations of transient antiferromagnetic correlations in quasi two dimensions in a photo-excited Mott insulator and present possible future routes of this fast-developing technique. The increasing number of X-ray free electron laser facilities not only enables tackling long-standing fundamental scientific problems, but also promises to unleash novel inelastic X-ray scattering spectroscopies. This article is part of the theme issue 'Measurement of ultrafast electronic and structural dynamics with X-rays'.
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Affiliation(s)
- Y. Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - D. G. Mazzone
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - D. Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - J. P. Hill
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - X. Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - S. Wall
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
| | - M. P. M. Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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12
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Chen XM, Mazzoli C, Cao Y, Thampy V, Barbour AM, Hu W, Lu M, Assefa TA, Miao H, Fabbris G, Gu GD, Tranquada JM, Dean MPM, Wilkins SB, Robinson IK. Charge density wave memory in a cuprate superconductor. Nat Commun 2019; 10:1435. [PMID: 30926816 PMCID: PMC6440992 DOI: 10.1038/s41467-019-09433-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [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: 07/13/2018] [Accepted: 03/11/2019] [Indexed: 11/09/2022] Open
Abstract
Although CDW correlations are a ubiquitous feature of the superconducting cuprates, their disparate properties suggest a crucial role for pinning the CDW to the lattice. Here, we report coherent resonant X-ray speckle correlation analysis, which directly determines the reproducibility of CDW domain patterns in La1.875Ba0.125CuO4 (LBCO 1/8) with thermal cycling. While CDW order is only observed below 54 K, where a structural phase transition creates inequivalent Cu-O bonds, we discover remarkably reproducible CDW domain memory upon repeated cycling to far higher temperatures. That memory is only lost on cycling to 240(3) K, which recovers the four-fold symmetry of the CuO2 planes. We infer that the structural features that develop below 240 K determine the CDW pinning landscape below 54 K. This opens a view into the complex coupling between charge and lattice degrees of freedom in superconducting cuprates.
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Affiliation(s)
- X M Chen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA. .,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Y Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - V Thampy
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - A M Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - W Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M Lu
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - T A Assefa
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - G Fabbris
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - G D Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - J M Tranquada
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - S B Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - I K Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA. .,London Centre for Nanotechnology, University College, Gower St., London, WC1E 6BT, UK.
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13
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Wang Y, Wang R, Kim J, Upton MH, Casa D, Gog T, Cao G, Kotliar G, Dean MPM, Liu X. Direct Detection of Dimer Orbitals in Ba_{5}AlIr_{2}O_{11}. Phys Rev Lett 2019; 122:106401. [PMID: 30932648 DOI: 10.1103/physrevlett.122.106401] [Citation(s) in RCA: 1] [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: 10/12/2018] [Indexed: 06/09/2023]
Abstract
The electronic states of many Mott insulators, including iridates, are often conceptualized in terms of localized atomic states such as the famous "J_{eff}=1/2 state." Although orbital hybridization can strongly modify such states and dramatically change the electronic properties of materials, probing this process is highly challenging. In this Letter, we directly detect and quantify the formation of dimer orbitals in an iridate material Ba_{5}AlIr_{2}O_{11} using resonant inelastic x-ray scattering. Sharp peaks corresponding to the excitations of dimer orbitals are observed and analyzed by a combination of density functional theory calculations and theoretical simulations based on an Ir-Ir cluster model. Such partially delocalized dimer states lead to a redefinition of the angular momentum of the electrons and changes in the magnetic and electronic behaviors of the material. We use this to explain the reduction of the observed magnetic moment with respect to predictions based on atomic states. This study opens new directions to study dimerization in a large family of materials, including solids, heterostructures, molecules, and transient states.
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Affiliation(s)
- Y Wang
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Ruitang Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jungho Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - D Casa
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - T Gog
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - G Cao
- Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - G Kotliar
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
- Physics and Astronomy Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
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14
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Meyers D, Cao Y, Fabbris G, Robinson NJ, Hao L, Frederick C, Traynor N, Yang J, Lin J, Upton MH, Casa D, Kim JW, Gog T, Karapetrova E, Choi Y, Haskel D, Ryan PJ, Horak L, Liu X, Liu J, Dean MPM. Magnetism in iridate heterostructures leveraged by structural distortions. Sci Rep 2019; 9:4263. [PMID: 30862782 PMCID: PMC6414659 DOI: 10.1038/s41598-019-39422-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [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: 10/25/2018] [Accepted: 01/18/2019] [Indexed: 11/09/2022] Open
Abstract
Fundamental control of magnetic coupling through heterostructure morphology is a prerequisite for rational engineering of magnetic ground states. We report the tuning of magnetic interactions in superlattices composed of single and bilayers of SrIrO3 inter-spaced with SrTiO3 in analogy to the Ruddlesden-Popper series iridates. Magnetic scattering shows predominately c-axis antiferromagnetic orientation of the magnetic moments for the bilayer, as in Sr3Ir2O7. However, the magnetic excitation gap, measured by resonant inelastic x-ray scattering, is quite different between the two structures, evidencing a significant change in the stability of the competing magnetic phases. In contrast, the single layer iridate hosts a more bulk-like gap. We find these changes are driven by bending of the c-axis Ir-O-Ir bond, which is much weaker in the single layer, and subsequent local environment changes, evidenced through x-ray diffraction and magnetic excitation modeling. Our findings demonstrate how large changes in the magnetic interactions can be tailored and probed in spin-orbit coupled heterostructures by engineering subtle structural modulations.
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Affiliation(s)
- D Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA.
| | - Yue Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - G Fabbris
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - Neil J Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - Lin Hao
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - C Frederick
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - N Traynor
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - J Yang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - Jiaqi Lin
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - M H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - D Casa
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - T Gog
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - E Karapetrova
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA
| | - P J Ryan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA.,School of Physical Sciences, Dublin City University, Dublin 9, Ireland
| | - Lukas Horak
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 3, Prague, 12116, Czech Republic
| | - X Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.,Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA.
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York, 11973, USA.
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15
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Meyers D, Nakatsukasa K, Mu S, Hao L, Yang J, Cao Y, Fabbris G, Miao H, Pelliciari J, McNally D, Dantz M, Paris E, Karapetrova E, Choi Y, Haskel D, Shafer P, Arenholz E, Schmitt T, Berlijn T, Johnston S, Liu J, Dean MPM. Decoupling Carrier Concentration and Electron-Phonon Coupling in Oxide Heterostructures Observed with Resonant Inelastic X-Ray Scattering. Phys Rev Lett 2018; 121:236802. [PMID: 30576191 DOI: 10.1103/physrevlett.121.236802] [Citation(s) in RCA: 3] [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: 06/20/2018] [Revised: 10/15/2018] [Indexed: 06/09/2023]
Abstract
We report the observation of multiple phonon satellite features in ultrathin superlattices of the form nSrIrO_{3}/mSrTiO_{3} using resonant inelastic x-ray scattering (RIXS). As the values of n and m vary, the energy loss spectra show a systematic evolution in the relative intensity of the phonon satellites. Using a closed-form solution for the RIXS cross section, we extract the variation in the electron-phonon coupling strength as a function of n and m. Combined with the negligible carrier doping into the SrTiO_{3} layers, these results indicate that the tuning of the electron-phonon coupling can be effectively decoupled from doping. This work both showcases a feasible method to extract the electron-phonon coupling in superlattices and unveils a potential route for tuning this coupling, which is often associated with superconductivity in SrTiO_{3}-based systems.
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Affiliation(s)
- D Meyers
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Ken Nakatsukasa
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Sai Mu
- Department of Condensed Matter Physics and Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Lin Hao
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Junyi Yang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Yue Cao
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Hu Miao
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J Pelliciari
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - D McNally
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Dantz
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - E Paris
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - E Karapetrova
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - P Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Thorsten Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Tom Berlijn
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Computational Science and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S Johnston
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Joint Institute of Advanced Materials at The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
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16
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Kim MG, Miao H, Gao B, Cheong SW, Mazzoli C, Barbour A, Hu W, Wilkins SB, Robinson IK, Dean MPM, Kiryukhin V. Imaging antiferromagnetic antiphase domain boundaries using magnetic Bragg diffraction phase contrast. Nat Commun 2018; 9:5013. [PMID: 30479333 PMCID: PMC6258669 DOI: 10.1038/s41467-018-07350-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [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: 08/09/2018] [Accepted: 10/24/2018] [Indexed: 11/09/2022] Open
Abstract
Manipulating magnetic domains is essential for many technological applications. Recent breakthroughs in Antiferromagnetic Spintronics brought up novel concepts for electronic device development. Imaging antiferromagnetic domains is of key importance to this field. Unfortunately, some of the basic domain types, such as antiphase domains, cannot be imaged by conventional techniques. Herein, we present a new domain projection imaging technique based on the localization of domain boundaries by resonant magnetic diffraction of coherent X rays. Contrast arises from reduction of the scattered intensity at the domain boundaries due to destructive interference effects. We demonstrate this approach by imaging antiphase domains in a collinear antiferromagnet Fe2Mo3O8, and observe evidence of domain wall interaction with a structural defect. This technique does not involve any numerical algorithms. It is fast, sensitive, produces large-scale images in a single-exposure measurement, and is applicable to a variety of magnetic domain types. Imaging the antiferromagnetic (AFM) domains facilitates the understanding and design of AFM spintronics but is still challenging. Here the authors show an imaging approach for antiphase domains in AFM Fe2Mo3O8 by resonantly scattered coherent soft X-rays, which is also applicable to collinear antiferromagnets.
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Affiliation(s)
- Min Gyu Kim
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - Hu Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Bin Gao
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - S-W Cheong
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - A Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Wen Hu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - S B Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - I K Robinson
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - V Kiryukhin
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854, USA.
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17
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Miao H, Zhang TT, Wang L, Meyers D, Said AH, Wang YL, Shi YG, Weng HM, Fang Z, Dean MPM. Observation of Double Weyl Phonons in Parity-Breaking FeSi. Phys Rev Lett 2018; 121:035302. [PMID: 30085785 DOI: 10.1103/physrevlett.121.035302] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Indexed: 06/08/2023]
Abstract
Condensed matter systems have now become a fertile ground to discover emerging topological quasiparticles with symmetry protected modes. While many studies have focused on fermionic excitations, the same conceptual framework can also be applied to bosons yielding new types of topological states. Motivated by Zhang et al.'s recent theoretical prediction of double Weyl phonons in transition metal monosilicides [Phys. Rev. Lett. 120, 016401 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.016401], we directly measure the phonon dispersion in parity-breaking FeSi using inelastic x-ray scattering. By comparing the experimental data with theoretical calculations, we make the first observation of double Weyl points in FeSi, which will be an ideal material to explore emerging bosonic excitations and its topologically nontrivial properties.
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Affiliation(s)
- H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - T T Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - L Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - D Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A H Said
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Y L Wang
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Y G Shi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - H M Weng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Z Fang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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18
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Hao L, Meyers D, Frederick C, Fabbris G, Yang J, Traynor N, Horak L, Kriegner D, Choi Y, Kim JW, Haskel D, Ryan PJ, Dean MPM, Liu J. Two-Dimensional J_{eff}=1/2 Antiferromagnetic Insulator Unraveled from Interlayer Exchange Coupling in Artificial Perovskite Iridate Superlattices. Phys Rev Lett 2017; 119:027204. [PMID: 28753323 DOI: 10.1103/physrevlett.119.027204] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Indexed: 06/07/2023]
Abstract
We report an experimental investigation of the two-dimensional J_{eff}=1/2 antiferromagnetic Mott insulator by varying the interlayer exchange coupling in [(SrIrO_{3})_{1}, (SrTiO_{3})_{m}] (m=1, 2 and 3) superlattices. Although all samples exhibited an insulating ground state with long-range magnetic order, temperature-dependent resistivity measurements showed a stronger insulating behavior in the m=2 and m=3 samples than the m=1 sample which displayed a clear kink at the magnetic transition. This difference indicates that the blocking effect of the excessive SrTiO_{3} layer enhances the effective electron-electron correlation and strengthens the Mott phase. The significant reduction of the Néel temperature from 150 K for m=1 to 40 K for m=2 demonstrates that the long-range order stability in the former is boosted by a substantial interlayer exchange coupling. Resonant x-ray magnetic scattering revealed that the interlayer exchange coupling has a switchable sign, depending on the SrTiO_{3} layer number m, for maintaining canting-induced weak ferromagnetism. The nearly unaltered transition temperature between the m=2 and the m=3 demonstrated that we have realized a two-dimensional antiferromagnet at finite temperatures with diminishing interlayer exchange coupling.
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Affiliation(s)
- Lin Hao
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - D Meyers
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Clayton Frederick
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Gilberto Fabbris
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Junyi Yang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Nathan Traynor
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Lukas Horak
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 3, Prague 12116, Czech Republic
| | - Dominik Kriegner
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 3, Prague 12116, Czech Republic
- Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 16253 Praha 6, Czech Republic
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Daniel Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Phil J Ryan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- School of Physical Sciences, Dublin City University, Dublin 9, Ireland
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
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19
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Fabbris G, Meyers D, Xu L, Katukuri VM, Hozoi L, Liu X, Chen ZY, Okamoto J, Schmitt T, Uldry A, Delley B, Gu GD, Prabhakaran D, Boothroyd AT, van den Brink J, Huang DJ, Dean MPM. Doping Dependence of Collective Spin and Orbital Excitations in the Spin-1 Quantum Antiferromagnet La_{2-x}Sr_{x}NiO_{4} Observed by X Rays. Phys Rev Lett 2017; 118:156402. [PMID: 28452512 DOI: 10.1103/physrevlett.118.156402] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Indexed: 05/23/2023]
Abstract
We report the first empirical demonstration that resonant inelastic x-ray scattering (RIXS) is sensitive to collective magnetic excitations in S=1 systems by probing the Ni L_{3} edge of La_{2-x}Sr_{x}NiO_{4} (x=0, 0.33, 0.45). The magnetic excitation peak is asymmetric, indicating the presence of single and multi-spin-flip excitations. As the hole doping level is increased, the zone boundary magnon energy is suppressed at a much larger rate than that in hole doped cuprates. Based on the analysis of the orbital and charge excitations observed by RIXS, we argue that this difference is related to the orbital character of the doped holes in these two families. This work establishes RIXS as a probe of fundamental magnetic interactions in nickelates opening the way towards studies of heterostructures and ultrafast pump-probe experiments.
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Affiliation(s)
- G Fabbris
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - D Meyers
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - L Xu
- Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstraße, 20, 01069 Dresden, Germany
| | - V M Katukuri
- Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstraße, 20, 01069 Dresden, Germany
| | - L Hozoi
- Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstraße, 20, 01069 Dresden, Germany
| | - X Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Z-Y Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - J Okamoto
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - T Schmitt
- Research Department "Synchotron Radiation and Nanotechnology", Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - A Uldry
- Condensed Matter Theory Group, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - B Delley
- Condensed Matter Theory Group, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - G D Gu
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - D Prabhakaran
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom
| | - A T Boothroyd
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom
| | - J van den Brink
- Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstraße, 20, 01069 Dresden, Germany
| | - D J Huang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
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20
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Chen XM, Thampy V, Mazzoli C, Barbour AM, Miao H, Gu GD, Cao Y, Tranquada JM, Dean MPM, Wilkins SB. Remarkable Stability of Charge Density Wave Order in La_{1.875}Ba_{0.125}CuO_{4}. Phys Rev Lett 2016; 117:167001. [PMID: 27792368 DOI: 10.1103/physrevlett.117.167001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Indexed: 06/06/2023]
Abstract
The occurrence of charge-density-wave (CDW) order in underdoped cuprates is now well established, although the precise nature of the CDW and its relationship with superconductivity is not. Theoretical proposals include contrasting ideas such as that pairing may be driven by CDW fluctuations or that static CDWs may intertwine with a spatially modulated superconducting wave function. We test the dynamics of CDW order in La_{1.825}Ba_{0.125}CuO_{4} by using x-ray photon correlation spectroscopy at the CDW wave vector, detected resonantly at the Cu L_{3} edge. We find that the CDW domains are strikingly static, with no evidence of significant fluctuations up to 2 ¾ h. We discuss the implications of these results for some of the competing theories.
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Affiliation(s)
- X M Chen
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - V Thampy
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Mazzoli
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A M Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - H Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G D Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Y Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J M Tranquada
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - M P M Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - S B Wilkins
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
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21
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Fabbris G, Meyers D, Okamoto J, Pelliciari J, Disa AS, Huang Y, Chen ZY, Wu WB, Chen CT, Ismail-Beigi S, Ahn CH, Walker FJ, Huang DJ, Schmitt T, Dean MPM. Orbital Engineering in Nickelate Heterostructures Driven by Anisotropic Oxygen Hybridization rather than Orbital Energy Levels. Phys Rev Lett 2016; 117:147401. [PMID: 27740843 DOI: 10.1103/physrevlett.117.147401] [Citation(s) in RCA: 4] [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: 03/17/2016] [Indexed: 06/06/2023]
Abstract
Resonant inelastic x-ray scattering is used to investigate the electronic origin of orbital polarization in nickelate heterostructures taking LaTiO_{3}-LaNiO_{3}-3×(LaAlO_{3}), a system with exceptionally large polarization, as a model system. We find that heterostructuring generates only minor changes in the Ni 3d orbital energy levels, contradicting the often-invoked picture in which changes in orbital energy levels generate orbital polarization. Instead, O K-edge x-ray absorption spectroscopy demonstrates that orbital polarization is caused by an anisotropic reconstruction of the oxygen ligand hole states. This provides an explanation for the limited success of theoretical predictions based on tuning orbital energy levels and implies that future theories should focus on anisotropic hybridization as the most effective means to drive large changes in electronic structure and realize novel emergent phenomena.
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Affiliation(s)
- G Fabbris
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - D Meyers
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J Okamoto
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - J Pelliciari
- Research Department "Synchrotron Radiation and Nanotechnology", Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - A S Disa
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Y Huang
- Research Department "Synchrotron Radiation and Nanotechnology", Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Z-Y Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - W B Wu
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - C T Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - S Ismail-Beigi
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA
| | - C H Ahn
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA
| | - F J Walker
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - D J Huang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - T Schmitt
- Research Department "Synchrotron Radiation and Nanotechnology", Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
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22
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Dean MPM, Cao Y, Liu X, Wall S, Zhu D, Mankowsky R, Thampy V, Chen XM, Vale JG, Casa D, Kim J, Said AH, Juhas P, Alonso-Mori R, Glownia JM, Robert A, Robinson J, Sikorski M, Song S, Kozina M, Lemke H, Patthey L, Owada S, Katayama T, Yabashi M, Tanaka Y, Togashi T, Liu J, Rayan Serrao C, Kim BJ, Huber L, Chang CL, McMorrow DF, Först M, Hill JP. Ultrafast energy- and momentum-resolved dynamics of magnetic correlations in the photo-doped Mott insulator Sr2IrO4. Nat Mater 2016; 15:601-5. [PMID: 27159018 DOI: 10.1038/nmat4641] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 04/07/2016] [Indexed: 05/07/2023]
Abstract
Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity. Recently, photo-excitation has been used to induce similarly exotic states transiently. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr2IrO4. We find that the non-equilibrium state, 2 ps after the excitation, exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. The marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.
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Affiliation(s)
- M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Y Cao
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - S Wall
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
| | - D Zhu
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R Mankowsky
- Max Planck Institute for the Structure and Dynamics of Matter, D-22761 Hamburg, Germany
- Center for Free Electron Laser Science, D-22761 Hamburg, Germany
| | - V Thampy
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X M Chen
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J G Vale
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - D Casa
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Jungho Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - A H Said
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - P Juhas
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - R Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J M Glownia
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - A Robert
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J Robinson
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M Sikorski
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - S Song
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M Kozina
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - H Lemke
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - L Patthey
- SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - S Owada
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - T Katayama
- Japan Synchrotron Radiation Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - M Yabashi
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | | | - T Togashi
- Japan Synchrotron Radiation Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - J Liu
- Department of Physics &Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - C Rayan Serrao
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA
| | - B J Kim
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
| | - L Huber
- Institute for Quantum Electronics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - C-L Chang
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, NL 9747AG, The Netherlands
| | - D F McMorrow
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - M Först
- Max Planck Institute for the Structure and Dynamics of Matter, D-22761 Hamburg, Germany
- Center for Free Electron Laser Science, D-22761 Hamburg, Germany
| | - J P Hill
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
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23
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Liu X, Dean MPM, Liu J, Chiuzbăian SG, Jaouen N, Nicolaou A, Yin WG, Rayan Serrao C, Ramesh R, Ding H, Hill JP. Probing single magnon excitations in Sr₂IrO₄ using O K-edge resonant inelastic x-ray scattering. J Phys Condens Matter 2015; 27:202202. [PMID: 25921058 DOI: 10.1088/0953-8984/27/20/202202] [Citation(s) in RCA: 2] [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] [Indexed: 06/04/2023]
Abstract
Resonant inelastic x-ray scattering (RIXS) at the L-edge of transition metal elements is now commonly used to probe single magnon excitations. Here we show that single magnon excitations can also be measured with RIXS at the K-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin-orbit coupling. This is demonstrated with oxygen K-edge RIXS experiments on the perovskite Sr2IrO4, where low energy peaks from single magnon excitations were observed. This new application of RIXS has excellent potential to be applied to a wide range of magnetic systems based on heavy elements, for which the L-edge RIXS energy resolution in the hard x-ray region is usually poor.
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Affiliation(s)
- X Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA. Collaborative Innovation Center of Quantum Matter, Beijing, People's Republic of China
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24
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Dean MPM, Dellea G, Springell RS, Yakhou-Harris F, Kummer K, Brookes NB, Liu X, Sun YJ, Strle J, Schmitt T, Braicovich L, Ghiringhelli G, Božović I, Hill JP. Persistence of magnetic excitations in La(2-x)Sr(x)CuO4 from the undoped insulator to the heavily overdoped non-superconducting metal. Nat Mater 2013; 12:1019-23. [PMID: 23913170 DOI: 10.1038/nmat3723] [Citation(s) in RCA: 19] [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: 03/06/2013] [Accepted: 06/26/2013] [Indexed: 05/23/2023]
Abstract
One of the most intensely studied scenarios of high-temperature superconductivity (HTS) postulates pairing by exchange of magnetic excitations. Indeed, such excitations have been observed up to optimal doping in the cuprates. In the heavily overdoped regime, neutron scattering measurements indicate that magnetic excitations have effectively disappeared, and this has been argued to cause the demise of HTS with overdoping. Here we use resonant inelastic X-ray scattering, which is sensitive to complementary parts of reciprocal space, to measure the evolution of the magnetic excitations in La(2-x)Sr(x)CuO4 across the entire phase diagram, from a strongly correlated insulator (x = 0) to a non-superconducting metal (x = 0.40). For x = 0, well-defined magnon excitations are observed. These magnons broaden with doping, but they persist with a similar dispersion and comparable intensity all the way to the non-superconducting, heavily overdoped metallic phase. The destruction of HTS with overdoping is therefore caused neither by the general disappearance nor by the overall softening of magnetic excitations. Other factors, such as the redistribution of spectral weight, must be considered.
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Affiliation(s)
- M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
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25
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Yin WG, Liu X, Tsvelik AM, Dean MPM, Upton MH, Kim J, Casa D, Said A, Gog T, Qi TF, Cao G, Hill JP. Ferromagnetic exchange anisotropy from antiferromagnetic superexchange in the mixed 3d-5d transition-metal compound Sr3CuIrO6. Phys Rev Lett 2013; 111:057202. [PMID: 23952439 DOI: 10.1103/physrevlett.111.057202] [Citation(s) in RCA: 4] [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: 02/01/2013] [Indexed: 06/02/2023]
Abstract
We report a combined experimental and theoretical study of the unusual ferromagnetism in the one-dimensional copper-iridium oxide Sr(3)CuIrO(6). Utilizing Ir L(3) edge resonant inelastic x-ray scattering, we reveal a large gap magnetic excitation spectrum. We find that it is caused by an unusual exchange anisotropy generating mechanism, namely, strong ferromagnetic anisotropy arising from antiferromagnetic superexchange, driven by the alternating strong and weak spin-orbit coupling on the 5d Ir and 3d Cu magnetic ions, respectively. From symmetry consideration, this novel mechanism is generally present in systems with edge-sharing Cu(2+)O(4) plaquettes and Ir(4+)O(6) octahedra. Our results point to unusual magnetic behavior to be expected in mixed 3d-5d transition-metal compounds via exchange pathways that are absent in pure 3d or 5d compounds.
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Affiliation(s)
- Wei-Guo Yin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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Dean MPM, James AJA, Springell RS, Liu X, Monney C, Zhou KJ, Konik RM, Wen JS, Xu ZJ, Gu GD, Strocov VN, Schmitt T, Hill JP. High-energy magnetic excitations in the cuprate superconductor Bi(2)Sr(2)CaCu(2)O(8+δ): towards a unified description of its electronic and magnetic degrees of freedom. Phys Rev Lett 2013; 110:147001. [PMID: 25167025 DOI: 10.1103/physrevlett.110.147001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Indexed: 06/03/2023]
Abstract
We investigate the high-energy magnetic excitation spectrum of the high-T(c) cuprate superconductor Bi(2)Sr(2)CaCu(2)O(8+δ) (Bi-2212) using Cu L(3) edge resonant inelastic x-ray scattering. Broad, dispersive magnetic excitations are observed, with a zone boundary energy of ∼ 300 meV and a weak dependence on doping. These excitations are strikingly similar to the bosons proposed to explain the high-energy "kink" observed in photoemission. A phenomenological calculation of the spin response, based on a parametrization of the the angle-resolved photoemission spectroscopy derived electronic structure and Yang-Rice-Zhang quasiparticles, provides a reasonable prediction of the energy dispersion of the observed magnetic excitations. These results indicate a possible unified framework to reconcile the magnetic and electronic properties of the cuprates and we discuss the advantages and disadvantages of such an approach.
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Affiliation(s)
- M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A J A James
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - R S Springell
- Royal Commission for the Exhibition of 1851 Research Fellow, Interface Analysis Centre, University of Bristol, Bristol BS2 8BS, United Kingdom and London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - X Liu
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Monney
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - K J Zhou
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - R M Konik
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - J S Wen
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Z J Xu
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - G D Gu
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Schmitt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J P Hill
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA
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Liu X, Katukuri VM, Hozoi L, Yin WG, Dean MPM, Upton MH, Kim J, Casa D, Said A, Gog T, Qi TF, Cao G, Tsvelik AM, van den Brink J, Hill JP. Testing the validity of the strong spin-orbit-coupling limit for octahedrally coordinated iridate compounds in a model system Sr3CuIrO6. Phys Rev Lett 2012; 109:157401. [PMID: 23102366 DOI: 10.1103/physrevlett.109.157401] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Indexed: 06/01/2023]
Abstract
The electronic structure of Sr3CuIrO6, a model system for the 5d Ir ion in an octahedral environment, is studied through a combination of resonant inelastic x-ray scattering and theoretical calculations. Resonant inelastic x-ray scattering spectra at the Ir L3 edge reveal an Ir t(2g) manifold that is split into three levels, in contrast to the expectations of the strong spin-orbit-coupling limit. Effective Hamiltonian and ab inito quantum chemistry calculations find a strikingly large noncubic crystal field splitting comparable to the spin-orbit coupling, which results in a strong mixing of the j(eff)=1/2 and j(eff)=3/2 states and modifies the isotropic wave functions on which many theoretical models are based.
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Affiliation(s)
- X Liu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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Dean MPM, Springell RS, Monney C, Zhou KJ, Pereiro J, Božović I, Dalla Piazza B, Rønnow HM, Morenzoni E, van den Brink J, Schmitt T, Hill JP. Spin excitations in a single La2CuO4 layer. Nat Mater 2012; 11:850-854. [PMID: 22941330 DOI: 10.1038/nmat3409] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 07/26/2012] [Indexed: 05/27/2023]
Abstract
Cuprates and other high-temperature superconductors consist of two-dimensional layers that are crucial to their properties. The dynamics of the quantum spins in these layers lie at the heart of the mystery of the cuprates. In bulk cuprates such as La(2)CuO(4), the presence of a weak coupling between the two-dimensional layers stabilizes a three-dimensional magnetic order up to high temperatures. In a truly two-dimensional system however, thermal spin fluctuations melt long-range order at any finite temperature. Here, we measure the spin response of isolated layers of La(2)CuO(4) that are only one-unit-cell-thick. We show that coherent magnetic excitations, magnons, known from the bulk order, persist even in a single layer of La(2)CuO(4), with no evidence for more complex correlations such as resonating valence bond correlations. These magnons are, therefore, well described by spin-wave theory (SWT). On the other hand, we also observe a high-energy magnetic continuum in the isotropic magnetic response that is not well described by two-magnon SWT, or indeed any existing theories.
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Affiliation(s)
- M P M Dean
- Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA.
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