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Zhang G, Pavarini E. Multiorbital Nature of Doped Sr_{2}IrO_{4}. PHYSICAL REVIEW LETTERS 2023; 131:036504. [PMID: 37540852 DOI: 10.1103/physrevlett.131.036504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 06/27/2023] [Indexed: 08/06/2023]
Abstract
The low-energy j_{eff}=1/2 band of Sr_{2}IrO_{4} bears stark resemblances with the x^{2}-y^{2} band of La_{2}CuO_{4}, and yet no superconductivity has been found so far by doping Sr_{2}IrO_{4}. Behind such a behavior could be inherent failures of the j_{eff}=1/2 picture, in particular when electrons or holes are introduced in the IrO_{2} planes. In view of this, here we reanalyze the j_{eff}=1/2 scenario. By using the local-density approximation plus dynamical mean-field theory approach, we show that the form of the effective j_{eff}=1/2 state is surprisingly stable upon doping. This supports the j_{eff}=1/2 picture. We show that, nevertheless, Sr_{2}IrO_{4} remains in essence a multiorbital system: The hybridization with the j_{eff}=3/2 orbitals sizably reduces the Mott gap by enhancing orbital degeneracy, and part of the holes go into the j_{eff}=3/2 channels. These effects cannot be reproduced by a simple effective screened Coulomb repulsion. In the optical conductivity spectra, multiorbital processes involving the j_{eff}=3/2 states contribute both to the Drude peak and to relatively low-energy features.
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Affiliation(s)
- Guoren Zhang
- School of Sciences, Nantong University, Nantong, 226019, People's Republic of China
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Eva Pavarini
- Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA High-Performance Computing, Forschungszentrum Jülich, 52425 Jülich, Germany
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2
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Wang H, Marshall M, Wang Z, Plumb KW, Greenblatt M, Zhu Y, Walker D, Xie W. Non-Centrosymmetric Sr 2IrO 4 Obtained Under High Pressure. Inorg Chem 2023; 62:2161-2168. [PMID: 36662554 DOI: 10.1021/acs.inorgchem.2c03835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Sr2IrO4 with strong spin-orbit coupling and Hubbard repulsion (U) hosts Mott insulating states. The similar crystal structure and magnetic and electronic properties, particularly the d-wave gap observed in Sr2IrO4 enhanced the analogies to the cuprate high-Tc superconductor, La2CuO4. The incomplete analogy was due to the lack of broken inversion symmetry phases observed in Sr2IrO4. Here, under high-pressure and high-temperature conditions, we report a noncentrosymmetric Sr2IrO4. The crystal structure and its noncentrosymmetric character were determined by single-crystal X-ray diffraction and high-resolution scanning transmission electron microscopy. The magnetic characterization confirms the Ir4+ with S = 1/2 at low temperature in Sr2IrO4 with magnetic ordering occurring at around 86 K, where a larger moment is observed than the ambient pressure Sr2IrO4. Moreover, the resistivity measurement shows three-dimensional Mott variable-range hopping (VRH) existed in the system. This noncentrosymmetric Sr2IrO4 phase appears to be a unique material that offers a further understanding of high-Tc superconductivity.
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Affiliation(s)
- Haozhe Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan48824, United States
| | - Madalynn Marshall
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey08854, United States
| | - Zhen Wang
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York11973, United States
| | - Kemp W Plumb
- Department of Physics, Brown University, Providence, Rhode Island02912, United States
| | - Martha Greenblatt
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey08854, United States
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York11973, United States
| | - David Walker
- Lamont Doherty Earth Observatory, Columbia University, Palisades, New York10964, United States
| | - Weiwei Xie
- Department of Chemistry, Michigan State University, East Lansing, Michigan48824, United States
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3
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Li H, Hao P, Zhang J, Gordon K, Linn AG, Chen X, Zheng H, Zhou X, Mitchell JF, Dessau DS. Electronic structure and correlations in planar trilayer nickelate Pr 4Ni 3O 8. SCIENCE ADVANCES 2023; 9:eade4418. [PMID: 36638179 PMCID: PMC9839319 DOI: 10.1126/sciadv.ade4418] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
The discovery of superconductivity in planar nickelates raises the question of how the electronic structure and correlations of Ni1+ compounds compare to those of the Cu2+ cuprate superconductors. Here, we present an angle-resolved photoemission spectroscopy (ARPES) study of the trilayer nickelate Pr4Ni3O8, revealing a Fermi surface resembling that of the hole-doped cuprates but with critical differences. Specifically, the main portions of the Fermi surface are extremely similar to that of the bilayer cuprates, with an additional piece that can accommodate additional hole doping. We find that the electronic correlations are about twice as strong in the nickelates and are almost k-independent, indicating that they originate from a local effect, likely the Mott interaction, whereas cuprate interactions are somewhat less local. Nevertheless, the nickelates still demonstrate the strange-metal behavior in the electron scattering rates. Understanding the similarities and differences between these two families of strongly correlated superconductors is an important challenge.
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Affiliation(s)
- Haoxiang Li
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
- Advanced Materials Thrust, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, Guangdong 511453, China
| | - Peipei Hao
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Junjie Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
- Institute of Crystal Materials and State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Kyle Gordon
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
| | - A. Garrison Linn
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Xinglong Chen
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Hong Zheng
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Xiaoqing Zhou
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
| | - J. F. Mitchell
- Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - D. S. Dessau
- Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA
- Center for Experiments on Quantum Materials, University of Colorado Boulder, Boulder, CO 80309, USA
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4
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Kim D, Ahn G, Schmehr J, Wilson SD, Moon SJ. Effects of the on-site energy on the electronic response of Sr3(Ir1−xMnx)2O7. Sci Rep 2022; 12:18957. [DOI: 10.1038/s41598-022-23593-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 11/02/2022] [Indexed: 11/10/2022] Open
Abstract
AbstractWe investigated the doping and temperature evolutions of the optical response of Sr3(Ir1−xMnx)2O7 single crystals with 0 ≤ x ≤ 0.36 by utilizing infrared spectroscopy. Substitution of 3d transition metal Mn ions into Sr3Ir2O7 is expected to induce an insulator-to-metal transition via the decrease in the magnitude of the spin–orbit coupling and the hole doping. In sharp contrast, our data reveal the resilience of the spin–orbit coupling and the incoherent character of the charge transport. Upon Mn substitution, an incoherent in-gap excitation at about 0.25 eV appeared with the decrease in the strength of the optical transitions between the effective total angular momentum Jeff bands of the Ir ions. The resonance energies of the optical transitions between the Jeff bands which are directly proportional to the magnitude of the spin–orbit coupling hardly varied. In addition to these evolutions of the low-energy response, Mn substitution led to the emergence of a distinct high-energy optical excitation at about 1.2 eV which is larger than the resonance energies of the optical transitions between the Jeff bands. This observation indicates that the Mn 3d states are located away from the Ir 5d states in energy and that the large difference in the on-site energies of the transition metal ions is responsible for the incoherent charge transport and the robustness of the spin–orbit coupling. The effect of Mn substitution was also registered in the temperature dependence of the electronic response. The anomaly in the optical response of the parent compound observed at the antiferromagnetic transition temperature is notably suppressed in the Mn-doped compounds despite the persistence of the long-range antiferromagnetic ordering. The suppression of the spin-charge coupling could be related to charge disproportionation of the Ir ions.
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Gong D, Yang J, Hao L, Horak L, Xin Y, Karapetrova E, Strempfer J, Choi Y, Kim JW, Ryan PJ, Liu J. Reconciling Monolayer and Bilayer J_{eff}=1/2 Square Lattices in Hybrid Oxide Superlattice. PHYSICAL REVIEW LETTERS 2022; 129:187201. [PMID: 36374692 DOI: 10.1103/physrevlett.129.187201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 08/08/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
The number of atomic layers confined in a two-dimensional structure is crucial for the electronic and magnetic properties. Single-layer and bilayer J_{eff}=1/2 square lattices are well-known examples where the presence of the extra layer turns the XY anisotropy to the c-axis anisotropy. We report on experimental realization of a hybrid SrIrO_{3}/SrTiO_{3} superlattice that integrates monolayer and bilayer square lattices in one layered structure. By synchrotron x-ray diffraction, resonant x-ray magnetic scattering, magnetization, and resistivity measurements, we found that the hybrid superlattice exhibits properties that are distinct from both the single-layer and bilayer systems and cannot be explained by a simple addition of them. In particular, the entire hybrid superlattice orders simultaneously through a single antiferromagnetic transition at temperatures similar to the bilayer system but with all the J_{eff}=1/2 moments mainly pointing in the ab plane similar to the single-layer system. The results show that bringing monolayer and bilayer with orthogonal properties in proximity to each other in a hybrid superlattice structure is a powerful way to stabilize a unique state not obtainable in a uniform structure.
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Affiliation(s)
- Dongliang Gong
- 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
| | - Lin Hao
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Anhui, Chinese Academy of Sciences, Hefei 230031, China
| | - Lukas Horak
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 3, Prague 12116, Czech Republic
| | - Yan Xin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Evguenia Karapetrova
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Jörg Strempfer
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Philip J Ryan
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Jian Liu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
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Nelson JN, Schreiber NJ, Georgescu AB, Goodge BH, Faeth BD, Parzyck CT, Zeledon C, Kourkoutis LF, Millis AJ, Georges A, Schlom DG, Shen KM. Interfacial charge transfer and persistent metallicity of ultrathin SrIrO 3/SrRuO 3 heterostructures. SCIENCE ADVANCES 2022; 8:eabj0481. [PMID: 35119924 PMCID: PMC8816341 DOI: 10.1126/sciadv.abj0481] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 12/13/2021] [Indexed: 05/28/2023]
Abstract
Interface quantum materials have yielded a plethora of previously unknown phenomena, including unconventional superconductivity, topological phases, and possible Majorana fermions. Typically, such states are detected at the interface between two insulating constituents by electrical transport, but whether either material is conducting, transport techniques become insensitive to interfacial properties. To overcome these limitations, we use angle-resolved photoemission spectroscopy and molecular beam epitaxy to reveal the electronic structure, charge transfer, doping profile, and carrier effective masses in a layer-by-layer fashion for the interface between the Dirac nodal-line semimetal SrIrO3 and the correlated metallic Weyl ferromagnet SrRuO3. We find that electrons are transferred from the SrIrO3 to SrRuO3, with an estimated screening length of λ = 3.2 ± 0.1 Å. In addition, we find that metallicity is preserved even down to a single SrIrO3 layer, where the dimensionality-driven metal-insulator transition typically observed in SrIrO3 is avoided because of strong hybridization of the Ir and Ru t2g states.
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Affiliation(s)
- Jocienne N. Nelson
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Nathaniel J. Schreiber
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Alexandru B. Georgescu
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY 10010, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Berit H. Goodge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | - Brendan D. Faeth
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Christopher T. Parzyck
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Cyrus Zeledon
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Lena F. Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA
| | - Andrew J. Millis
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY 10010, USA
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Antoine Georges
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY 10010, USA
- Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
- CPHT, CNRS, Ecole Polytechnique, IP Paris, F-91128 Palaiseau, France
- DQMP, Universitè de Genéve, 24 quai Ernest Ansermet, CH-1211 Genéve, Suisse
| | - Darrell G. Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA
- Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin, Germany
| | - Kyle M. Shen
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA
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Dhingra A, Komesu T, Kumar S, Shimada K, Zhang L, Hong X, Dowben PA. Electronic band structure of iridates. MATERIALS HORIZONS 2021; 8:2151-2168. [PMID: 34846422 DOI: 10.1039/d1mh00063b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this review, an attempt has been made to compare the electronic structures of various 5d iridates (iridium oxides), with an effort to note the common features and differences. Both experimental studies, especially angle-resolved photoemission spectroscopy (ARPES) results, and first-principles band structure calculations have been discussed. This brings to focus the fact that the electronic structures and magnetic properties of the high-Z 5d transition iridates depend on the intricate interplay of strong electron correlation, strong (relativistic) spin-orbit coupling, lattice distortion, and the dimensionality of the system. For example, in the thin film limit, SrIrO3 exhibits a metal-insulator transition that corresponds to the dimensionality crossover, with the band structure resembling that of bulk Sr2IrO4.
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Affiliation(s)
- Archit Dhingra
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, Theodore Jorgensen Hall, University of Nebraska, 855 N 16th, P. O. Box 880299, Lincoln, Nebraska 68588-0299, USA.
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8
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Fruchter L, Brouet V. The 'dark phase' in Sr 2Ir 1-xRh xO 4revealed by Seebeck and Hall measurements. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:215602. [PMID: 33652426 DOI: 10.1088/1361-648x/abeb45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
It was found that, although isovalent, Rh substituted for Ir in Sr2IrO4may trap one electron inducing effective hole doping of Ir sites. Transport and thermoelectric measurements on Sr2Ir1-xRhxO4single crystals presented here reveal the existence of an electron-like contribution to transport, in addition to the hole-doped one. As no electron band shows up in ARPES measurements, this points to the possibility that this hidden electron may delocalize in disordered clusters.
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Affiliation(s)
- L Fruchter
- Laboratoire de Physique des Solides, C.N.R.S., Université Paris-Sud Université Paris-Saclay, 91405 Orsay Cedex, France
| | - V Brouet
- Laboratoire de Physique des Solides, C.N.R.S., Université Paris-Sud Université Paris-Saclay, 91405 Orsay Cedex, France
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9
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Advanced First-Principle Modeling of Relativistic Ruddlesden—Popper Strontium Iridates. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11062527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this review, we provide a survey of the application of advanced first-principle methods on the theoretical modeling and understanding of novel electronic, optical, and magnetic properties of the spin-orbit coupled Ruddlesden–Popper series of iridates Srn+1IrnO3n+1 (n = 1, 2, and ∞). After a brief description of the basic aspects of the adopted methods (noncollinear local spin density approximation plus an on-site Coulomb interaction (LSDA+U), constrained random phase approximation (cRPA), GW, and Bethe–Salpeter equation (BSE)), we present and discuss select results. We show that a detailed phase diagrams of the metal–insulator transition and magnetic phase transition can be constructed by inspecting the evolution of electronic and magnetic properties as a function of Hubbard U, spin–orbit coupling (SOC) strength, and dimensionality n, which provide clear evidence for the crucial role played by SOC and U in establishing a relativistic (Dirac) Mott–Hubbard insulating state in Sr2IrO4 and Sr3Ir2O7. To characterize the ground-state phases, we quantify the most relevant energy scales fully ab initio—crystal field energy, Hubbard U, and SOC constant of three compounds—and discuss the quasiparticle band structures in detail by comparing GW and LSDA+U data. We examine the different magnetic ground states of structurally similar n = 1 and n = 2 compounds and clarify that the origin of the in-plane canted antiferromagnetic (AFM) state of Sr2IrO4 arises from competition between isotropic exchange and Dzyaloshinskii–Moriya (DM) interactions whereas the collinear AFM state of Sr3Ir2O7 is due to strong interlayer magnetic coupling. Finally, we report the dimensionality controlled metal–insulator transition across the series by computing their optical transitions and conductivity spectra at the GW+BSE level from the the quasi two-dimensional insulating n = 1 and 2 phases to the three-dimensional metallic n=∞ phase.
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10
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Affiliation(s)
- Alex Zunger
- Energy Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Oleksandr I. Malyi
- Energy Institute, University of Colorado, Boulder, Colorado 80309, United States
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11
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Ahn G, Schmehr JL, Porter Z, Wilson SD, Moon SJ. Doping and temperature evolutions of optical response of Sr 3(Ir 1-xRu x) 2O 7. Sci Rep 2020; 10:22340. [PMID: 33339856 PMCID: PMC7749133 DOI: 10.1038/s41598-020-79263-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 12/01/2020] [Indexed: 11/09/2022] Open
Abstract
We report on optical spectroscopic study of the Sr3(Ir1-xRux)2O7 system over a wide doping regime. We find that the changes in the electronic structure occur in the limited range of the concentration of Ru ions where the insulator-metal transition occurs. In the insulating regime, the electronic structure associated with the effective total angular momentum Jeff = 1/2 Mott state remains robust against Ru doping, indicating the localization of the doped holes. Upon entering the metallic regime, the Mott gap collapses and the Drude-like peak with strange metallic character appears. The evolution of the electronic structure registered in the optical data can be explained in terms of a percolative insulator-metal transition. The phonon spectra display anomalous doping evolution of the lineshapes. While the phonon modes of the compounds deep in the insulating and metallic regimes are almost symmetric, those of the semiconducting compound with x = 0.34 in close proximity to the doping-driven insulator-metal transition show a pronounced asymmetry. The temperature evolution of the phonon modes of the x = 0.34 compound reveals the asymmetry is enhanced in the antiferromagnetic state. We discuss roles of the S = 1 spins of the Ru ions and charge excitations for the conspicuous lineshape asymmetry of the x = 0.34 compound.
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Affiliation(s)
- Gihyeon Ahn
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea
| | - J L Schmehr
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - Z Porter
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - S D Wilson
- Materials Department, University of California, Santa Barbara, CA, 93106, USA
| | - S J Moon
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea. .,Research Institute of Natural Science, Hanyang University, Seoul, 04763, Republic of Korea.
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12
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Li S, Drueke E, Porter Z, Jin W, Lu Z, Smirnov D, Merlin R, Wilson SD, Sun K, Zhao L. Symmetry-Resolved Two-Magnon Excitations in a Strong Spin-Orbit-Coupled Bilayer Antiferromagnet. PHYSICAL REVIEW LETTERS 2020; 125:087202. [PMID: 32909791 DOI: 10.1103/physrevlett.125.087202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
We used a combination of polarized Raman spectroscopy and spin wave calculations to study magnetic excitations in the strong spin-orbit-coupled bilayer perovskite antiferromagnet Sr_{3}Ir_{2}O_{7}. We observed two broad Raman features at ∼800 and ∼1400 cm^{-1} arising from magnetic excitations. Unconventionally, the ∼800 cm^{-1} feature is fully symmetric (A_{1g}) with respect to the underlying tetragonal (D_{4h}) crystal lattice which, together with its broad line shape, definitively rules out the possibility of a single magnon excitation as its origin. In contrast, the ∼1400 cm^{-1} feature shows up in both the A_{1g} and B_{2g} channels. From spin wave and two-magnon scattering cross-section calculations of a tetragonal bilayer antiferromagnet, we identified the ∼800 cm^{-1} (1400 cm^{-1}) feature as two-magnon excitations with pairs of magnons from the zone-center Γ point (zone-boundary van Hove singularity X point). We further found that this zone-center two-magnon scattering is unique to bilayer perovskite magnets which host an optical branch in addition to the acoustic branch, as compared to their single layer counterparts. This zone-center two-magnon mode is distinct in symmetry from the time-reversal symmetry broken "spin wave gap" and "phase mode" proposed to explain the ∼92 meV (742 cm^{-1}) gap in resonant inelastic x-ray spectroscopy magnetic excitation spectra of Sr_{3}Ir_{2}O_{7}.
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Affiliation(s)
- Siwen Li
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Elizabeth Drueke
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Zach Porter
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - Wencan Jin
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Zhengguang Lu
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
- Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - Roberto Merlin
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Stephen D Wilson
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - Kai Sun
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Liuyan Zhao
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
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13
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Lu C, Liu JM. The J eff = 1/2 Antiferromagnet Sr 2 IrO 4 : A Golden Avenue toward New Physics and Functions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904508. [PMID: 31667943 DOI: 10.1002/adma.201904508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 09/12/2019] [Indexed: 06/10/2023]
Abstract
Iridates have been providing a fertile ground for studying emergent phases of matter that arise from the delicate interplay of various fundamental interactions with approximate energy scale. Among these highly focused quantum materials, the perovskite Sr2 IrO4 , which belongs to the Ruddlesden-Popper series, stands out and has been intensively addressed in the last decade, since it hosts a novel Jeff = 1/2 state that is a profound manifestation of strong spin-orbit coupling. Moreover, the Jeff = 1/2 state represents a rare example of iridates that is better understood both theoretically and experimentally. Here, Sr2 IrO4 is taken as an example to review the recent advances of the Jeff = 1/2 state in two aspects: materials fundamentals and functionality potentials. In the fundamentals part, the basic issues for the layered canted antiferromagnetic order of the Jeff = 1/2 magnetic moments in Sr2 IrO4 are illustrated, and then the progress of the antiferromagnetic order modulation through diverse routes is highlighted. Subsequently, for the functionality potentials, fascinating properties such as atomic-scale giant magnetoresistance, anisotropic magnetoresistance, and nonvolatile memory, are addressed. To conclude, prospective remarks and an outlook are given.
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Affiliation(s)
- Chengliang Lu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jun-Ming Liu
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and Institute for Advanced Materials, South China Normal University, Guangzhou, 510006, China
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14
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Sarte PM, Wilson SD, Attfield JP, Stock C. Magnetic fluctuations and the spin-orbit interaction in Mott insulating CoO. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:374011. [PMID: 32554874 DOI: 10.1088/1361-648x/ab8498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 03/30/2020] [Indexed: 06/11/2023]
Abstract
Motivated by the presence of an unquenched orbital angular momentum in CoO, a team at Chalk River, including a recently hired research officer Roger Cowley, performed the first inelastic neutron scattering experiments on the classic Mott insulator [Sakuraiet al1968Phys. Rev.167510]. Despite identifying two magnon modes at the zone boundary, the team was unable to parameterise the low energy magnetic excitation spectrum belowTNusing conventional pseudo-bosonic approaches, instead achieving only qualitative agreement. It would not be for another 40 years that Roger, now at Oxford and motivated by the discovery of the high-Tccuprate superconductors [Bednorz and Muller 1986Z. Phys. B64189], would make another attempt at the parameterisation of the magnetic excitation spectrum that had previously alluded him at the start of his career. Upon his return to CoO, Roger found a system embroiled in controversy, with some of its most fundamental parameters still remaining undetermined. Faced with such a formidable task, Roger performed a series of inelastic neutron scattering experiments in the early 2010s on both CoO and a magnetically dilute structural analogue Mg0.97Co0.03O. These experiments would prove instrumental in the determination of both single-ion [Cowleyet al2013Phys. Rev. B88205117] and cooperative magnetic parameters [Sarteet al2018Phys. Rev. B98024415] for CoO. Both these sets of parameters would eventually be used in a spin-orbit exciton model [Sarteet al2019Phys. Rev. B100075143], developed by his longtime friend and collaborator Bill Buyers, to successfully parameterise the complex spectrum that both measured at Chalk River almost 50 years prior. The story of CoO is of one that has come full circle, one filled with both spectacular failures and intermittent, yet profound, little victories.
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Affiliation(s)
- P M Sarte
- California NanoSystems Institute, University of California, Santa Barbara, California 93106-6105, United States of America
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States of America
- School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
- Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - S D Wilson
- California NanoSystems Institute, University of California, Santa Barbara, California 93106-6105, United States of America
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States of America
| | - J P Attfield
- School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
- Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - C Stock
- Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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15
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Nelson JN, Parzyck CT, Faeth BD, Kawasaki JK, Schlom DG, Shen KM. Mott gap collapse in lightly hole-doped Sr 2-xK xIrO 4. Nat Commun 2020; 11:2597. [PMID: 32444617 PMCID: PMC7244596 DOI: 10.1038/s41467-020-16425-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 04/23/2020] [Indexed: 11/09/2022] Open
Abstract
The evolution of Sr2IrO4 upon carrier doping has been a subject of intense interest, due to its similarities to the parent cuprates, yet the intrinsic behaviour of Sr2IrO4 upon hole doping remains enigmatic. Here, we synthesize and investigate hole-doped Sr2-xKxIrO4 utilizing a combination of reactive oxide molecular-beam epitaxy, substitutional diffusion and in-situ angle-resolved photoemission spectroscopy. Upon hole doping, we observe the formation of a coherent, two-band Fermi surface, consisting of both hole pockets centred at (π, 0) and electron pockets centred at (π/2, π/2). In particular, the strong similarities between the Fermi surface topology and quasiparticle band structure of hole- and electron-doped Sr2IrO4 are striking given the different internal structure of doped electrons versus holes.
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Affiliation(s)
- J N Nelson
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York, 14853, USA
| | - C T Parzyck
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York, 14853, USA
| | - B D Faeth
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York, 14853, USA
| | - J K Kawasaki
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York, 14853, USA.,Department of Materials Science and Engineering, Cornell University, Ithaca, New York, 14853, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York, 14853, USA.,Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin, 53706, USA
| | - D G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York, 14853, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York, 14853, USA
| | - K M Shen
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York, 14853, USA. .,Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York, 14853, USA.
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16
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Xu B, Marsik P, Sheveleva E, Lyzwa F, Louat A, Brouet V, Munzar D, Bernhard C. Optical Signature of a Crossover from Mott- to Slater-Type Gap in Sr_{2}Ir_{1-x}Rh_{x}O_{4}. PHYSICAL REVIEW LETTERS 2020; 124:027402. [PMID: 32004046 DOI: 10.1103/physrevlett.124.027402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Indexed: 06/10/2023]
Abstract
With optical spectroscopy we provide evidence that the insulator-metal transition in Sr_{2}Ir_{1-x}Rh_{x}O_{4} occurs close to a crossover from the Mott- to the Slater-type. The Mott gap at x=0 persists to high temperature and evolves without an anomaly across the Néel temperature, T_{N}. Upon Rh doping, it collapses rather rapidly and vanishes around x=0.055. Notably, just as the Mott gap vanishes yet another gap appears that is of the Slater-type and develops right below T_{N}. This Slater gap is only partial and is accompanied by a reduced scattering rate of the remaining free carriers, similar as in the parent compounds of the iron arsenide superconductors.
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Affiliation(s)
- B Xu
- University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - P Marsik
- University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - E Sheveleva
- University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - F Lyzwa
- University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
| | - A Louat
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - V Brouet
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - D Munzar
- Department of Condensed Matter Physics, Faculty of Science, and Central European Institute of Technology, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic
| | - C Bernhard
- University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
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17
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Lenz B, Martins C, Biermann S. Spectral functions of Sr 2IrO 4: theory versus experiment. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:293001. [PMID: 30921786 DOI: 10.1088/1361-648x/ab146a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The spin-orbit Mott insulator Sr2IrO4 has attracted a lot of interest in recent years from theory and experiment due to its close connection to isostructural high-temperature copper oxide superconductors. Despite not being superconductive, its spectral features closely resemble those of the cuprates, including Fermi surface and pseudogap properties. In this article, we review and extend recent work in the theoretical description of the spectral function of pure and electron-doped Sr2IrO4 based on a cluster extension of dynamical mean-field theory ('oriented-cluster DMFT') and compare it to available angle-resolved photoemission data. Current theories provide surprisingly good agreement for pure and electron-doped Sr2IrO4, both in the paramagnetic and antiferromagnetic phases. Most notably, one obtains simple explanations for the experimentally observed steep feature around the M point and the pseudo-gap-like spectral feature in electron-doped Sr2IrO4.
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Affiliation(s)
- B Lenz
- CPHT, Ecole Polytechnique, CNRS, Université Paris-Saclay, Route de Saclay, 91128 Palaiseau, France
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18
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Schmehr JL, Zoghlin E, Porter Z, Wang X, Ruff JPC, Tian W, Islam Z, Wilson SD. Preferential quenching of 5d antiferromagnetic order in Sr 3(Ir 1-x Mn x ) 2O 7. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:244003. [PMID: 30861499 DOI: 10.1088/1361-648x/ab0ef9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The breakdown of [Formula: see text] antiferromagnetism in the limit of strong disorder is studied in Sr3(Ir1-x Mn x )2O7. Upon Mn-substitution, antiferromagnetic ordering of the Ir cations becomes increasingly two-dimensional, resulting in the complete suppression of long-range Ir magnetic order above [Formula: see text]. Long-range antiferromagnetism however persists on the Mn sites to higher Mn concentrations (x > 0.25) and is necessarily mediated via a random network of majority Ir sites. Our data suggest a shift in the Mn valence from Mn4+ to Mn3+ at intermediate doping levels, which in turn generates nonmagnetic Ir5+ sites and suppresses long-range order within the Ir network. The collapse of long-range [Formula: see text] antiferromagnetism and the survival of percolating antiferromagnetic order on Mn-sites demonstrates a complex 3d-5d exchange process that surprisingly enables minority Mn spins to order far below the conventional percolation threshold for a bilayer square lattice.
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Affiliation(s)
- Julian L Schmehr
- Materials Department, University of California, Santa Barbara, CA 93106, United States of America
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19
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Wang BB, Wang W, Yu SL, Li JX. Particle–hole fluctuations and possible superconductivity in doped α-RuCl 3*. CHINESE PHYSICS B 2019; 28:057402. [DOI: 10.1088/1674-1056/28/5/057402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Abstract
We study various particle–hole excitations and possible superconducting pairings mediated by these fluctuations in doped α-RuCl3 by using multi-band Hubbard model with all t2g orbitals. By performing a random-phase-approximation (RPA) analysis, we find that among all particle–hole excitations, the j
eff = 1/2 pseudospin fluctuations are dominant, suggesting the robustness of j
eff = 1/2 picture even in the doped systems. We also find that the most favorable superconducting state has a d-wave pairing symmetry.
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20
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Anderson R, Wang F, Xu P, Venu V, Trotzky S, Chevy F, Thywissen JH. Conductivity Spectrum of Ultracold Atoms in an Optical Lattice. PHYSICAL REVIEW LETTERS 2019; 122:153602. [PMID: 31050527 DOI: 10.1103/physrevlett.122.153602] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Indexed: 06/09/2023]
Abstract
We measure the conductivity of neutral fermions in a cubic optical lattice. Using in situ fluorescence microscopy, we observe the alternating current resultant from a single-frequency uniform force applied by displacement of a weak harmonic trapping potential. In the linear response regime, a neutral-particle analog of Ohm's law gives the conductivity as the ratio of total current to force. For various lattice depths, temperatures, interaction strengths, and fillings, we measure both real and imaginary conductivity, up to a frequency sufficient to capture the transport dynamics within the lowest band. The spectral width of the real conductivity reveals the current dissipation rate in the lattice, and the integrated spectral weight is related to thermodynamic properties of the system through a sum rule. The global conductivity decreases with increased band-averaged effective mass, which at high temperatures approaches a T-linear regime. Relaxation of current is observed to require a finite lattice depth, which breaks Galilean invariance and enables damping through collisions between fermions.
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Affiliation(s)
- Rhys Anderson
- Department of Physics, University of Toronto, Ontario M5S 1A7 Canada
| | - Fudong Wang
- Department of Physics, University of Toronto, Ontario M5S 1A7 Canada
| | - Peihang Xu
- Department of Physics, University of Toronto, Ontario M5S 1A7 Canada
| | - Vijin Venu
- Department of Physics, University of Toronto, Ontario M5S 1A7 Canada
| | - Stefan Trotzky
- Department of Physics, University of Toronto, Ontario M5S 1A7 Canada
| | - Frédéric Chevy
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Université, Collège de France, 24 Rue Lhomond, 75005 Paris, France
| | - Joseph H Thywissen
- Department of Physics, University of Toronto, Ontario M5S 1A7 Canada
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1M1 Canada
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21
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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] [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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22
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Wang Z, Okada Y, O'Neal J, Zhou W, Walkup D, Dhital C, Hogan T, Clancy P, Kim YJ, Hu YF, Santos LH, Wilson SD, Trivedi N, Madhavan V. Disorder induced power-law gaps in an insulator-metal Mott transition. Proc Natl Acad Sci U S A 2018; 115:11198-11202. [PMID: 30322914 PMCID: PMC6217382 DOI: 10.1073/pnas.1808056115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A correlated material in the vicinity of an insulator-metal transition (IMT) exhibits rich phenomenology and a variety of interesting phases. A common avenue to induce IMTs in Mott insulators is doping, which inevitably leads to disorder. While disorder is well known to create electronic inhomogeneity, recent theoretical studies have indicated that it may play an unexpected and much more profound role in controlling the properties of Mott systems. Theory predicts that disorder might play a role in driving a Mott insulator across an IMT, with the emergent metallic state hosting a power-law suppression of the density of states (with exponent close to 1; V-shaped gap) centered at the Fermi energy. Such V-shaped gaps have been observed in Mott systems, but their origins are as-yet unknown. To investigate this, we use scanning tunneling microscopy and spectroscopy to study isovalent Ru substitutions in Sr3(Ir1-xRux)2O7 (0 ≤ x ≤ 0.5) which drive the system into an antiferromagnetic, metallic state. Our experiments reveal that many core features of the IMT, such as power-law density of states, pinning of the Fermi energy with increasing disorder, and persistence of antiferromagnetism, can be understood as universal features of a disordered Mott system near an IMT and suggest that V-shaped gaps may be an inevitable consequence of disorder in doped Mott insulators.
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Affiliation(s)
- Zhenyu Wang
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801
- Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801
| | - Yoshinori Okada
- Quantum Materials Science Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Jared O'Neal
- Mathematics Department, The Ohio State University, Columbus, OH 43210
| | - Wenwen Zhou
- Department of Physics, Boston College, Chestnut Hill, MA 02467
| | - Daniel Walkup
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Chetan Dhital
- Department of Physics, Kennesaw State University, Marietta, GA 30060
| | - Tom Hogan
- Materials Department, University of California, Santa Barbara, CA 93106
| | - Patrick Clancy
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
| | - Young-June Kim
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
| | - Y F Hu
- Canadian Light Source, Saskatoon, SK S7N 2V3, Canada
| | - Luiz H Santos
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801
- Institute for Condensed Matter Theory, University of Illinois Urbana-Champaign, Urbana, IL 61801
| | - Stephen D Wilson
- Materials Department, University of California, Santa Barbara, CA 93106
| | - Nandini Trivedi
- Department of Physics, The Ohio State University, Columbus, Ohio 43210
| | - Vidya Madhavan
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801;
- Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801
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23
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Kim SY, Lee MC, Han G, Kratochvilova M, Yun S, Moon SJ, Sohn C, Park JG, Kim C, Noh TW. Spectroscopic Studies on the Metal-Insulator Transition Mechanism in Correlated Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1704777. [PMID: 29761925 DOI: 10.1002/adma.201704777] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/18/2017] [Indexed: 06/08/2023]
Abstract
The metal-insulator transition (MIT) in correlated materials is a novel phenomenon that accompanies a large change in resistivity, often many orders of magnitude. It is important in its own right but its switching behavior in resistivity can be useful for device applications. From the material physics point of view, the starting point of the research on the MIT should be to understand the microscopic mechanism. Here, an overview of recent efforts to unravel the microscopic mechanisms for various types of MITs in correlated materials is provided. Research has focused on transition metal oxides (TMOs), but transition metal chalcogenides have also been studied. Along the way, a new class of MIT materials is discovered, the so-called relativistic Mott insulators in 5d TMOs. Distortions in the MO6 (M = transition metal) octahedron are found to have a large and peculiar effect on the band structure in an orbital dependent way, possibly paving a way to the orbital selective Mott transition. In the final section, the character of the materials suitable for applications is summarized, followed by a brief discussion of some of the efforts to control MITs in correlated materials, including a dynamical approach using light.
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Affiliation(s)
- So Yeun Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Min-Cheol Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Garam Han
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Marie Kratochvilova
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seokhwan Yun
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Soon Jae Moon
- Department of Physics, Hanyang University, Seoul, Republic of Korea
| | - Changhee Sohn
- Materials Science and Technology Division, Oak Ridge National Laboratory, TN, 37831, USA
| | - Je-Geun Park
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
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24
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Terashima K, Paris E, Salas-Colera E, Simonelli L, Joseph B, Wakita T, Horigane K, Fujii M, Kobayashi K, Horie R, Akimitsu J, Muraoka Y, Yokoya T, Saini NL. Determination of the local structure of Sr 2-xM xIrO 4 (M = K, La) as a function of doping and temperature. Phys Chem Chem Phys 2018; 20:23783-23788. [PMID: 30199083 DOI: 10.1039/c8cp03756f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The local structure of correlated spin-orbit insulator Sr2-xMxIrO4 (M = K, La) has been investigated by Ir L3-edge extended X-ray absorption fine structure measurements. The measurements were performed as a function of temperature for different dopings induced by substitution of Sr with La or K. It is found that Ir-O bonds have strong covalency and they hardly show any change across the Néel temperature. In the studied doping range, neither Ir-O bonds nor their dynamics, measured by their mean square relative displacements, show any appreciable change upon carrier doping, indicating the possibility of nanoscale phase separation in the doped system. On the other hand, there is a large increase of the static disorder in Ir-Sr correlation, larger for K doping than La doping. Similarities and differences with respect to the local lattice displacements in cuprates are briefly discussed.
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Affiliation(s)
- Kensei Terashima
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530, Japan.
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25
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Zhao HD, Terzic J, Zheng H, Ni YF, Zhang Y, Ye F, Schlottmann P, Cao G. Decoupling of magnetism and electric transport in single-crystal (Sr 1-x A x ) 2IrO 4 (A = Ca or Ba). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:245801. [PMID: 29722680 DOI: 10.1088/1361-648x/aac23d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report a systematical structural, transport and magnetic study of Ca or Ba doped Sr2IrO4 single crystals. Isoelectronically substituting Ca2+ (up to 15%) or Ba2+ (up to 4%) ion for the Sr2+ ion provides no additional charge carriers but effectively changes the lattice parameters in Sr2IrO4. In particular, 15% Ca doping considerably reduces the c-axis and the unit cell by nearly 0.45% and 1.00%, respectively. These significant, anisotropic compressions in the lattice parameters conspicuously cause no change in the Néel temperature which remains at 240 K, but drastically reduces the electrical resistivity by up to five orders of magnitude or even precipitates a sharp insulator-to-metal transition at lower temperatures, i.e. the vanishing insulating state accompanies an unchanged Néel temperature in (Sr1-x A x )2IrO4. This observation brings to light an intriguing difference between chemical pressure and applied pressure, the latter of which does suppress the long-range magnetic order in Sr2IrO4. This difference reveals the importance of the Ir1-O2-Ir1 bond angle and homogenous volume compression in determining the magnetic ground state. All results, along with a comparison drawn with results of Tb and La doped Sr2IrO4, underscore that the magnetic transition plays a nonessential role in the formation of the charge gap in the spin-orbit-tuned iridate.
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Affiliation(s)
- H D Zhao
- Department of Physics, University of Colorado at Boulder, CO 80309, United States of America
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Cao G, Schlottmann P. The challenge of spin-orbit-tuned ground states in iridates: a key issues review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:042502. [PMID: 29353815 DOI: 10.1088/1361-6633/aaa979] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Effects of spin-orbit interactions in condensed matter are an important and rapidly evolving topic. Strong competition between spin-orbit, on-site Coulomb and crystalline electric field interactions in iridates drives exotic quantum states that are unique to this group of materials. In particular, the 'J eff = ½' Mott state served as an early signal that the combined effect of strong spin-orbit and Coulomb interactions in iridates has unique, intriguing consequences. In this Key Issues Review, we survey some current experimental studies of iridates. In essence, these materials tend to defy conventional wisdom: absence of conventional correlations between magnetic and insulating states, avoidance of metallization at high pressures, 'S-shaped' I-V characteristic, emergence of an odd-parity hidden order, etc. It is particularly intriguing that there exist conspicuous discrepancies between current experimental results and theoretical proposals that address superconducting, topological and quantum spin liquid phases. This class of materials, in which the lattice degrees of freedom play a critical role seldom seen in other materials, evidently presents some profound intellectual challenges that call for more investigations both experimentally and theoretically. Physical properties unique to these materials may help unlock a world of possibilities for functional materials and devices. We emphasize that, given the rapidly developing nature of this field, this Key Issues Review is by no means an exhaustive report of the current state of experimental studies of iridates.
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Affiliation(s)
- Gang Cao
- Department of Physics, University of Colorado at Boulder, Boulder, CO 80309, United States of America
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Malvestuto M, Ciprian R, Caretta A, Casarin B, Parmigiani F. Ultrafast magnetodynamics with free-electron lasers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:053002. [PMID: 29315080 DOI: 10.1088/1361-648x/aaa211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The study of ultrafast magnetodynamics has entered a new era thanks to the groundbreaking technological advances in free-electron laser (FEL) light sources. The advent of these light sources has made possible unprecedented experimental schemes for time-resolved x-ray magneto-optic spectroscopies, which are now paving the road for exploring the ultimate limits of out-of-equilibrium magnetic phenomena. In particular, these studies will provide insights into elementary mechanisms governing spin and orbital dynamics, therefore contributing to the development of ultrafast devices for relevant magnetic technologies. This topical review focuses on recent advancement in the study of non-equilibrium magnetic phenomena from the perspective of time-resolved extreme ultra violet (EUV) and soft x-ray spectroscopies at FELs with highlights of some important experimental results.
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Affiliation(s)
- Marco Malvestuto
- Elettra-Sincrotrone Trieste S.C.p.A. Strada Statale 14-km 163.5 in AREA Science Park 34149 Basovizza, Trieste, Italy
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Unidirectional spin density wave state in metallic (Sr 1-xLa x ) 2IrO 4. Nat Commun 2018; 9:103. [PMID: 29317642 PMCID: PMC5760634 DOI: 10.1038/s41467-017-02647-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 12/14/2017] [Indexed: 12/03/2022] Open
Abstract
Materials that exhibit both strong spin–orbit coupling and electron correlation effects are predicted to host numerous new electronic states. One prominent example is the Jeff = 1/2 Mott state in Sr2IrO4, where introducing carriers is predicted to manifest high temperature superconductivity analogous to the S = 1/2 Mott state of La2CuO4. While bulk superconductivity currently remains elusive, anomalous quasiparticle behaviors paralleling those in the cuprates such as pseudogap formation and the formation of a d-wave gap are observed upon electron-doping Sr2IrO4. Here we establish a magnetic parallel between electron-doped Sr2IrO4 and hole-doped La2CuO4 by unveiling a spin density wave state in electron-doped Sr2IrO4. Our magnetic resonant X-ray scattering data reveal the presence of an incommensurate magnetic state reminiscent of the diagonal spin density wave state observed in the monolayer cuprate (La1−xSrx)2CuO4. This link supports the conjecture that the quenched Mott phases in electron-doped Sr2IrO4 and hole-doped La2CuO4 support common competing electronic phases. Electron-doped Sr2IrO4 is an intriguing material for searching for an unconventional superconducting state. Here the authors demonstrate that a spin density wave state exists in the metallic phase of electron-doped Sr2IrO4 which provides a link between the electronic phase diagrams of the hole-doped cuprates and the electron-doped iridates.
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Li H, Zhou X, Nummy T, Zhang J, Pardo V, Pickett WE, Mitchell JF, Dessau DS. Fermiology and electron dynamics of trilayer nickelate La 4Ni 3O 10. Nat Commun 2017; 8:704. [PMID: 28951567 PMCID: PMC5614968 DOI: 10.1038/s41467-017-00777-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/26/2017] [Indexed: 11/09/2022] Open
Abstract
Layered nickelates have the potential for exotic physics similar to high TC superconducting cuprates as they have similar crystal structures and these transition metals are neighbors in the periodic table. Here we present an angle-resolved photoemission spectroscopy (ARPES) study of the trilayer nickelate La4Ni3O10 revealing its electronic structure and correlations, finding strong resemblances to the cuprates as well as a few key differences. We find a large hole Fermi surface that closely resembles the Fermi surface of optimally hole-doped cuprates, including its \documentclass[12pt]{minimal}
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\begin{document}$$d_{x^2-y^2}$$\end{document}dx2-y2 band, while it has an extra band of principally \documentclass[12pt]{minimal}
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\begin{document}$$d_{3z^2-r^2}$$\end{document}d3z2-r2 orbital character, which presents a low temperature energy gap. These aspects drive the nickelate physics, with the differences from the cuprate electronic structure potentially shedding light on the origin of superconductivity in the cuprates. Exploration of the electronic structure of nickelates with similar crystal structure to cuprates may shed a light on the origin of high Tc superconductivity. Here, Li et al. report strong resemblances and key differences of the electronic structure of trilayer nickelate La4Ni3O10 compared to the cuprate superconductors.
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Affiliation(s)
- Haoxiang Li
- Department of Physics, University of Colorado at Boulder, Boulder, CO, 80309, USA
| | - Xiaoqing Zhou
- Department of Physics, University of Colorado at Boulder, Boulder, CO, 80309, USA
| | - Thomas Nummy
- Department of Physics, University of Colorado at Boulder, Boulder, CO, 80309, USA
| | - Junjie Zhang
- Material Science Division, Argonne National Lab, Argonne, IL, 60439, USA
| | - Victor Pardo
- Departamento de Fisica Aplicada and Instituto de Investigacions Tecnoloxicas, Universidade de Santiago de Compostela, Campus Sur s/n, E-15782, Santiago de Compostela, Spain
| | - Warren E Pickett
- Department of Physics, University of California, Davis, CA, 95616, USA
| | - J F Mitchell
- Material Science Division, Argonne National Lab, Argonne, IL, 60439, USA
| | - D S Dessau
- Department of Physics, University of Colorado at Boulder, Boulder, CO, 80309, USA. .,Center for Experiments on Quantum Materials, University of Colorado at Boulder, Boulder, CO, 80309, USA.
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Pärschke EM, Wohlfeld K, Foyevtsova K, van den Brink J. Correlation induced electron-hole asymmetry in quasi- two-dimensional iridates. Nat Commun 2017; 8:686. [PMID: 28947738 PMCID: PMC5612937 DOI: 10.1038/s41467-017-00818-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 07/25/2017] [Indexed: 11/09/2022] Open
Abstract
The resemblance of crystallographic and magnetic structures of the quasi-two-dimensional iridates Ba2IrO4 and Sr2IrO4 to La2CuO4 points at an analogy to cuprate high-Tc superconductors, even if spin-orbit coupling is very strong in iridates. Here we examine this analogy for the motion of a charge (hole or electron) added to the antiferromagnetic ground state. We show that correlation effects render the hole and electron case in iridates very different. An added electron forms a spin polaron, similar to the cuprates, but the situation of a removed electron is far more complex. Many-body 5d 4 configurations form which can be singlet and triplet states of total angular momentum that strongly affect the hole motion. This not only has ramifications for the interpretation of (inverse-)photoemission experiments but also demonstrates that correlation physics renders electron- and hole-doped iridates fundamentally different.Some iridate compounds such as Sr2IrO4 have electronic and atomic structures similar to quasi-2D copper oxides, raising the prospect of high temperature superconductivity. Here, the authors show that there is significant electron-hole asymmetry in iridates, contrary to expectations from the cuprates.
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Affiliation(s)
| | - Krzysztof Wohlfeld
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02093, Warsaw, Poland
| | - Kateryna Foyevtsova
- University of British Columbia, 6224 Agricultural Road, Vancouver, BC, Canada, V6T 1Z1
| | - Jeroen van den Brink
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany.,Institute for Theoretical Physics, TU Dresden, 01069, Dresden, Germany
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Abstract
We report on infrared spectroscopy experiments on the electronic response in (Sr1-x La x )2IrO4 (x = 0, 0.021, and 0.067). Our data show that electron doping induced by La substitution leads to an insulator-to-metal transition. The evolution of the electronic structure across the transition reveals the robustness of the strong electronic correlations against the electron doping. The conductivity data of the metallic compound show the signature of the pseudogap that bears close similarity to the analogous studies of the pseudogap in the underdoped cuprates. While the low energy conductivity of the metallic compound is barely frequency dependent, the formation of the pseudogap is revealed by the gradual suppression of the featureless conductivity below a threshold frequency of about 17 meV. The threshold structure develops below about 100 K which is in the vicinity of the onset of the short-range antiferromagnetic order. Our results demonstrate that the electronic correlations play a crucial role in the anomalous charge dynamics in the (Sr1-x La x )2IrO4 system.
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Time-reversal symmetry breaking hidden order in Sr 2(Ir,Rh)O 4. Nat Commun 2017; 8:15119. [PMID: 28436436 PMCID: PMC5413971 DOI: 10.1038/ncomms15119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 03/02/2017] [Indexed: 11/08/2022] Open
Abstract
Layered 5d transition iridium oxides, Sr2(Ir,Rh)O4, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr2IrO4, is a nearly ideal two-dimensional pseudospin-1/2 Heisenberg antiferromagnet, similarly to the insulating parent compound of high-temperature superconducting copper oxides. Using polarized neutron diffraction, we here report a hidden magnetic order in pure and doped Sr2(Ir,Rh)O4, distinct from the usual antiferromagnetic pseudospin ordering. We find that time-reversal symmetry is broken while the lattice translation invariance is preserved in the hidden order phase. The onset temperature matches that of the odd-parity hidden order recently highlighted using optical second-harmonic generation experiments. The novel magnetic order and broken symmetries can be explained by the loop-current model, previously predicted for the copper oxide superconductors.
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Chu H, Zhao L, de la Torre A, Hogan T, Wilson SD, Hsieh D. A charge density wave-like instability in a doped spin-orbit-assisted weak Mott insulator. NATURE MATERIALS 2017; 16:200-203. [PMID: 28092687 DOI: 10.1038/nmat4836] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 11/21/2016] [Indexed: 06/06/2023]
Abstract
Layered perovskite iridates realize a rare class of Mott insulators that are predicted to be strongly spin-orbit coupled analogues of the parent state of cuprate high-temperature superconductors. Recent discoveries of pseudogap, magnetic multipolar ordered and possible d-wave superconducting phases in doped Sr2IrO4 have reinforced this analogy among the single layer variants. However, unlike the bilayer cuprates, no electronic instabilities have been reported in the doped bilayer iridate Sr3Ir2O7. Here we show that Sr3Ir2O7 realizes a weak Mott state with no cuprate analogue by using ultrafast time-resolved optical reflectivity to uncover an intimate connection between its insulating gap and antiferromagnetism. However, we detect a subtle charge density wave-like Fermi surface instability in metallic electron doped Sr3Ir2O7 at temperatures (TDW) close to 200 K via the coherent oscillations of its collective modes, which is reminiscent of that observed in cuprates. The absence of any signatures of a new spatial periodicity below TDW from diffraction, scanning tunnelling and photoemission based probes suggests an unconventional and possibly short-ranged nature of this density wave order.
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Affiliation(s)
- H Chu
- Department of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - L Zhao
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
| | - A de la Torre
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
| | - T Hogan
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - S D Wilson
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - D Hsieh
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
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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. NATURE MATERIALS 2016; 15:601-5. [PMID: 27159018 DOI: 10.1038/nmat4641] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [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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