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Kim H, Kim JK, Kwon J, Kim J, Kim HWJ, Ha S, Kim K, Lee W, Kim J, Cho GY, Heo H, Jang J, Sahle CJ, Longo A, Strempfer J, Fabbris G, Choi Y, Haskel D, Kim J, Kim JW, Kim BJ. Quantum spin nematic phase in a square-lattice iridate. Nature 2024; 625:264-269. [PMID: 38093009 DOI: 10.1038/s41586-023-06829-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Accepted: 11/03/2023] [Indexed: 01/12/2024]
Abstract
Spin nematic is a magnetic analogue of classical liquid crystals, a fourth state of matter exhibiting characteristics of both liquid and solid1,2. Particularly intriguing is a valence-bond spin nematic3-5, in which spins are quantum entangled to form a multipolar order without breaking time-reversal symmetry, but its unambiguous experimental realization remains elusive. Here we establish a spin nematic phase in the square-lattice iridate Sr2IrO4, which approximately realizes a pseudospin one-half Heisenberg antiferromagnet in the strong spin-orbit coupling limit6-9. Upon cooling, the transition into the spin nematic phase at TC ≈ 263 K is marked by a divergence in the static spin quadrupole susceptibility extracted from our Raman spectra and concomitant emergence of a collective mode associated with the spontaneous breaking of rotational symmetries. The quadrupolar order persists in the antiferromagnetic phase below TN ≈ 230 K and becomes directly observable through its interference with the antiferromagnetic order in resonant X-ray diffraction, which allows us to uniquely determine its spatial structure. Further, we find using resonant inelastic X-ray scattering a complete breakdown of coherent magnon excitations at short-wavelength scales, suggesting a many-body quantum entanglement in the antiferromagnetic state10,11. Taken together, our results reveal a quantum order underlying the Néel antiferromagnet that is widely believed to be intimately connected to the mechanism of high-temperature superconductivity12,13.
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Affiliation(s)
- Hoon Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Jin-Kwang Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Junyoung Kwon
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Jimin Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Hyun-Woo J Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Seunghyeok Ha
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Kwangrae Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Wonjun Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Jonghwan Kim
- Center for Van der Waals Quantum Solids, Institute for Basic Science, Pohang, Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, Korea
| | - Gil Young Cho
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea
| | - Hyeokjun Heo
- Department of Physics and Astronomy, Seoul National University, Seoul, South Korea
| | - Joonho Jang
- Department of Physics and Astronomy, Seoul National University, Seoul, South Korea
| | - C J Sahle
- ESRF, The European Synchrotron, Grenoble, France
| | - A Longo
- ESRF, The European Synchrotron, Grenoble, France
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)-CNR, UOS Palermo, Palermo, Italy
| | - J Strempfer
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - Y Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - Jungho Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - J -W Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - B J Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, South Korea.
- Department of Physics, Pohang University of Science and Technology, Pohang, South Korea.
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2
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de la Torre A, Zager B, Bahrami F, Upton MH, Kim J, Fabbris G, Lee GH, Yang W, Haskel D, Tafti F, Plumb KW. Momentum-independent magnetic excitation continuum in the honeycomb iridate H 3LiIr 2O 6. Nat Commun 2023; 14:5018. [PMID: 37596328 PMCID: PMC10439105 DOI: 10.1038/s41467-023-40769-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: 02/08/2023] [Accepted: 08/07/2023] [Indexed: 08/20/2023] Open
Abstract
Understanding the interplay between the inherent disorder and the correlated fluctuating-spin ground state is a key element in the search for quantum spin liquids. H3LiIr2O6 is considered to be a spin liquid that is proximate to the Kitaev-limit quantum spin liquid. Its ground state shows no magnetic order or spin freezing as expected for the spin liquid state. However, hydrogen zero-point motion and stacking faults are known to be present. The resulting bond disorder has been invoked to explain the existence of unexpected low-energy spin excitations, although data interpretation remains challenging. Here, we use resonant X-ray spectroscopies to map the collective excitations in H3LiIr2O6 and characterize its magnetic state. In the low-temperature correlated state, we reveal a broad bandwidth of magnetic excitations. The central energy and the high-energy tail of the continuum are consistent with expectations for dominant ferromagnetic Kitaev interactions between dynamically fluctuating spins. Furthermore, the absence of a momentum dependence to these excitations are consistent with disorder-induced broken translational invariance. Our low-energy data and the energy and width of the crystal field excitations support an interpretation of H3LiIr2O6 as a disordered topological spin liquid in close proximity to bond-disordered versions of the Kitaev quantum spin liquid.
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Affiliation(s)
- A de la Torre
- Department of Physics, Brown University, Providence, RI, 02912, USA.
| | - B Zager
- Department of Physics, Brown University, Providence, RI, 02912, USA
| | - F Bahrami
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA
| | - M H Upton
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - J Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - G-H Lee
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, 94720, USA
| | - W Yang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, 94720, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - F Tafti
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA
| | - K W Plumb
- Department of Physics, Brown University, Providence, RI, 02912, USA.
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3
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Arias-Egido E, Laguna-Marco MA, Piquer C, Jiménez-Cavero P, Lucas I, Morellón L, Gallego F, Rivera-Calzada A, Cabero-Piris M, Santamaria J, Fabbris G, Haskel D, Boada R, Díaz-Moreno S. Dimensionality-driven metal-insulator transition in spin-orbit-coupled IrO 2. Nanoscale 2021; 13:17125-17135. [PMID: 34635906 DOI: 10.1039/d1nr04207f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A metal-insulator transition is observed in spin-orbit-coupled IrO2 thin films upon reduction of the film thickness. In the epitaxially grown samples, the critical thickness (t ∼ 1.5-2.2 nm) is found to depend on growth orientation (001), (100) or (110). Interestingly from the applied point of view, the insulating behavior is found even in polycrystalline ultrathin films. By analyzing the experimental electrical response with various theoretical models, we find good fits to the Efros-Shklovskii-VRH and the Arrhenius-type behaviors, which suggests an important role of electron correlations in determining the electrical properties of IrO2. Our magnetic measurements also point to a significant role of magnetic order. Altogether, our results would point to a mixed Slater- and Mott-type of insulator.
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Affiliation(s)
- E Arias-Egido
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC - Universidad de Zaragoza, Zaragoza 50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza 50009, Spain
| | - M A Laguna-Marco
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC - Universidad de Zaragoza, Zaragoza 50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza 50009, Spain
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
| | - C Piquer
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC - Universidad de Zaragoza, Zaragoza 50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza 50009, Spain
| | - P Jiménez-Cavero
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC - Universidad de Zaragoza, Zaragoza 50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza 50009, Spain
| | - I Lucas
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC - Universidad de Zaragoza, Zaragoza 50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza 50009, Spain
| | - L Morellón
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC - Universidad de Zaragoza, Zaragoza 50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza 50009, Spain
| | - F Gallego
- GFMC, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | | | - M Cabero-Piris
- ICTS - Centro Nacional de Microscopía Electrónica, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J Santamaria
- GFMC, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Laboratorio de Heteroestructuras con aplicación en spintrónica, Unidad Asociada UCM/CSIC, 28049 Madrid, Spain
- GFMC, Instituto de Magnetismo Aplicado, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - R Boada
- Department of Chemistry Universitat Autonoma de Barcelona 08193 Bellaterra, Barcelona, Spain
- Diamond Light Source Ltd Harwell Science and Innovation Campus Didcot, Oxfordshire OX11 0DE, UK
| | - S Díaz-Moreno
- Diamond Light Source Ltd Harwell Science and Innovation Campus Didcot, Oxfordshire OX11 0DE, UK
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4
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Yoo MW, Tornos J, Sander A, Lin LF, Mohanta N, Peralta A, Sanchez-Manzano D, Gallego F, Haskel D, Freeland JW, Keavney DJ, Choi Y, Strempfer J, Wang X, Cabero M, Vasili HB, Valvidares M, Sanchez-Santolino G, Gonzalez-Calbet JM, Rivera A, Leon C, Rosenkranz S, Bibes M, Barthelemy A, Anane A, Dagotto E, Okamoto S, te Velthuis SGE, Santamaria J, Villegas JE. Large intrinsic anomalous Hall effect in SrIrO 3 induced by magnetic proximity effect. Nat Commun 2021; 12:3283. [PMID: 34078889 PMCID: PMC8172877 DOI: 10.1038/s41467-021-23489-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [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: 06/17/2020] [Accepted: 04/25/2021] [Indexed: 02/04/2023] Open
Abstract
The anomalous Hall effect (AHE) is an intriguing transport phenomenon occurring typically in ferromagnets as a consequence of broken time reversal symmetry and spin-orbit interaction. It can be caused by two microscopically distinct mechanisms, namely, by skew or side-jump scattering due to chiral features of the disorder scattering, or by an intrinsic contribution directly linked to the topological properties of the Bloch states. Here we show that the AHE can be artificially engineered in materials in which it is originally absent by combining the effects of symmetry breaking, spin orbit interaction and proximity-induced magnetism. In particular, we find a strikingly large AHE that emerges at the interface between a ferromagnetic manganite (La0.7Sr0.3MnO3) and a semimetallic iridate (SrIrO3). It is intrinsic and originates in the proximity-induced magnetism present in the narrow bands of strong spin-orbit coupling material SrIrO3, which yields values of anomalous Hall conductivity and Hall angle as high as those observed in bulk transition-metal ferromagnets. These results demonstrate the interplay between correlated electron physics and topological phenomena at interfaces between 3d ferromagnets and strong spin-orbit coupling 5d oxides and trace an exciting path towards future topological spintronics at oxide interfaces.
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Affiliation(s)
- Myoung-Woo Yoo
- grid.460789.40000 0004 4910 6535Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - J. Tornos
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - A. Sander
- grid.460789.40000 0004 4910 6535Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Ling-Fang Lin
- grid.411461.70000 0001 2315 1184Department of Physics and Astronomy, University of Tennessee, Knoxville, TN USA ,grid.263826.b0000 0004 1761 0489School of Physics, Southeast University, Nanjing, China
| | - Narayan Mohanta
- grid.135519.a0000 0004 0446 2659Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - A. Peralta
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - D. Sanchez-Manzano
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - F. Gallego
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - D. Haskel
- grid.187073.a0000 0001 1939 4845Advanced Photon Source Argonne National Laboratory, Lemont, IL USA
| | - J. W. Freeland
- grid.187073.a0000 0001 1939 4845Advanced Photon Source Argonne National Laboratory, Lemont, IL USA
| | - D. J. Keavney
- grid.187073.a0000 0001 1939 4845Advanced Photon Source Argonne National Laboratory, Lemont, IL USA
| | - Y. Choi
- grid.187073.a0000 0001 1939 4845Advanced Photon Source Argonne National Laboratory, Lemont, IL USA
| | - J. Strempfer
- grid.187073.a0000 0001 1939 4845Advanced Photon Source Argonne National Laboratory, Lemont, IL USA
| | - X. Wang
- grid.253355.70000 0001 2192 5641Department of Physics, Bryn Mawr College, Bryn Mawr, PA USA
| | - M. Cabero
- grid.5515.40000000119578126IMDEA Nanoscience Campus Universidad Autonoma, Cantoblanco, Spain ,grid.4795.f0000 0001 2157 7667Centro Nacional de Microscopia Electronica, Universidad Complutense, Madrid, Spain
| | - Hari Babu Vasili
- grid.423639.9CELLS-ALBA Synchrotron Radiation Facility, Cerdanyola del Valles, Spain
| | - Manuel Valvidares
- grid.423639.9CELLS-ALBA Synchrotron Radiation Facility, Cerdanyola del Valles, Spain
| | - G. Sanchez-Santolino
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - J. M. Gonzalez-Calbet
- grid.4795.f0000 0001 2157 7667Centro Nacional de Microscopia Electronica, Universidad Complutense, Madrid, Spain ,grid.4795.f0000 0001 2157 7667Department Quimica Inorganica, Facultad de Quimica, Universidad Complutense, Madrid, Spain
| | - A. Rivera
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - C. Leon
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - S. Rosenkranz
- grid.187073.a0000 0001 1939 4845Materials Science Division, Argonne National Laboratory, Lemont, IL USA
| | - M. Bibes
- grid.460789.40000 0004 4910 6535Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - A. Barthelemy
- grid.460789.40000 0004 4910 6535Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - A. Anane
- grid.460789.40000 0004 4910 6535Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
| | - Elbio Dagotto
- grid.411461.70000 0001 2315 1184Department of Physics and Astronomy, University of Tennessee, Knoxville, TN USA ,grid.135519.a0000 0004 0446 2659Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - S. Okamoto
- grid.135519.a0000 0004 0446 2659Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - S. G. E. te Velthuis
- grid.187073.a0000 0001 1939 4845Materials Science Division, Argonne National Laboratory, Lemont, IL USA
| | - J. Santamaria
- grid.4795.f0000 0001 2157 7667GFMC, Dept. Fisica de Materiales, Facultad de Fisica, Universidad Complutense, Madrid, Spain
| | - Javier E. Villegas
- grid.460789.40000 0004 4910 6535Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France
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5
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Haskel D, Fabbris G, Kim JH, Veiga LSI, Mardegan JRL, Escanhoela CA, Chikara S, Struzhkin V, Senthil T, Kim BJ, Cao G, Kim JW. Possible Quantum Paramagnetism in Compressed Sr_{2}IrO_{4}. Phys Rev Lett 2020; 124:067201. [PMID: 32109088 DOI: 10.1103/physrevlett.124.067201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
The effect of compression on the magnetic ground state of Sr_{2}IrO_{4} is studied with x-ray resonant techniques in the diamond anvil cell. The weak interlayer exchange coupling between square-planar 2D IrO_{2} layers is readily modified upon compression, with a crossover between magnetic structures around 7 GPa mimicking the effect of an applied magnetic field at ambient pressure. Higher pressures drive an order-disorder magnetic phase transition with no magnetic order detected above 17-20 GPa. The persistence of strong exchange interactions between J_{eff}=1/2 magnetic moments within the insulating IrO_{2} layers up to at least 35 GPa points to a highly frustrated magnetic state in compressed Sr_{2}IrO_{4}, opening the door for realization of novel quantum paramagnetic phases driven by extended 5d orbitals with entangled spin and orbital degrees of freedom.
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Affiliation(s)
- D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J H Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - L S I Veiga
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Brazilian Synchrotron Light Laboratory (LNLS), Campinas, São Paulo 13083-970, Brazil
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo 13083-859, Brazil
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - J R L Mardegan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo 13083-859, Brazil
| | - C A Escanhoela
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Brazilian Synchrotron Light Laboratory (LNLS), Campinas, São Paulo 13083-970, Brazil
| | - S Chikara
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - V Struzhkin
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - T Senthil
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - B J Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), 77 Cheongam-Ro, Pohang 790-784, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, South Korea
| | - G Cao
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - J-W Kim
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
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6
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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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7
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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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8
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Song J, Fabbris G, Bi W, Haskel D, Schilling JS. Pressure-Induced Superconductivity in Elemental Ytterbium Metal. Phys Rev Lett 2018; 121:037004. [PMID: 30085803 DOI: 10.1103/physrevlett.121.037004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/30/2018] [Indexed: 06/08/2023]
Abstract
Ytterbium (Yb) metal is divalent and nonmagnetic (4f^{14} configuration). Under pressure its valence increases significantly leading to the expectation that magnetic instabilities and other highly correlated electron effects may appear before a stable trivalent state is reached (4f^{13} configuration). We carried out electrical resistivity and ac magnetic susceptibility measurements to 179 GPa over the temperature range 1.4-295 K. No evidence for magnetic order is observed. However, Yb becomes a superconductor at 86 GPa with T_{c}≃1.4 K, increasing to 4.6 K at 179 GPa. X-ray absorption spectroscopy shows that Yb remains mixed valent to at least 125 GPa, pointing to an active role of f electrons in the emergence of superconductivity in this simple, elemental solid.
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Affiliation(s)
- J Song
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - W Bi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J S Schilling
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
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9
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Wallace MK, LaBarre PG, Li J, Pi ST, Pickett WE, Dessau DS, Haskel D, Ramirez AP, Subramanian MA. Local Moment Instability of Os in Honeycomb Li 2.15Os 0.85O 3. Sci Rep 2018; 8:6605. [PMID: 29700362 PMCID: PMC5919924 DOI: 10.1038/s41598-018-25028-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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: 03/08/2018] [Accepted: 04/13/2018] [Indexed: 11/10/2022] Open
Abstract
Compounds with honeycomb structures occupied by strong spin orbit coupled (SOC) moments are considered to be candidate Kitaev quantum spin liquids. Here we present the first example of Os on a honeycomb structure, Li2.15(3)Os0.85(3)O3 (C2/c, a = 5.09 Å, b = 8.81 Å, c = 9.83 Å, β = 99.3°). Neutron diffraction shows large site disorder in the honeycomb layer and X-ray absorption spectroscopy indicates a valence state of Os (4.7 ± 0.2), consistent with the nominal concentration. We observe a transport band gap of Δ = 243 ± 23 meV, a large van Vleck susceptibility, and an effective moment of 0.85 μB, much lower than expected from 70% Os(+5). No evidence of long range order is found above 0.10 K but a spin glass-like peak in ac-susceptibility is observed at 0.5 K. The specific heat displays an impurity spin contribution in addition to a power law ∝T(0.63±0.06). Applied density functional theory (DFT) leads to a reduced moment, suggesting incipient itineracy of the valence electrons, and finding evidence that Li over stoichiometry leads to Os(4+)−Os(5+) mixed valence. This local picture is discussed in light of the site disorder and a possible underlying quantum spin liquid state.
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Affiliation(s)
- M K Wallace
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA
| | - P G LaBarre
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Jun Li
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA
| | - S-T Pi
- Department of Physics, University of California Davis, Davis, CA, 95616, USA
| | - W E Pickett
- Department of Physics, University of California Davis, Davis, CA, 95616, USA
| | - D S Dessau
- Department of Physics, University of Colorado, Denver, CO, 80309, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - A P Ramirez
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - M A Subramanian
- Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA.
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10
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Cui Q, Cheng JG, Fan W, Taylor AE, Calder S, McGuire MA, Yan JQ, Meyers D, Li X, Cai YQ, Jiao YY, Choi Y, Haskel D, Gotou H, Uwatoko Y, Chakhalian J, Christianson AD, Yunoki S, Goodenough JB, Zhou JS. Slater Insulator in Iridate Perovskites with Strong Spin-Orbit Coupling. Phys Rev Lett 2016; 117:176603. [PMID: 27824456 DOI: 10.1103/physrevlett.117.176603] [Citation(s) in RCA: 3] [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: 05/18/2016] [Indexed: 06/06/2023]
Abstract
The perovskite SrIrO_{3} is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent Sn^{4+} for Ir^{4+} in the SrIr_{1-x}Sn_{x}O_{3} perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic (AF) phase at T_{N}≥225 K. The continuous change of the cell volume as detected by x-ray diffraction and the λ-shape transition of the specific heat on cooling through T_{N} demonstrate that the metal-insulator transition is of second order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type-G AF spin ordering below T_{N}. Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below T_{N} in the same way as proposed by Slater.
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Affiliation(s)
- Q Cui
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - W Fan
- Computational Condensed Matter Physical Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - A E Taylor
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - S Calder
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - M A McGuire
- Materials Science and Technology Division, Oak Ridge National Laboratory, Tennessee 37831, USA
| | - J-Q Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - D Meyers
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - X Li
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - Y Q Cai
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - Y Y Jiao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Y Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - H Gotou
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581, Japan
| | - Y Uwatoko
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581, Japan
| | - J Chakhalian
- Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - A D Christianson
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - S Yunoki
- Computational Condensed Matter Physical Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
- Computational Materials Science Research Team, RIKEN Advanced Institute for Computational Science (AICS), Kobe, Hyogo 650-0047, Japan
- Computational Quantum Matter Research Team, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - J B Goodenough
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
| | - J-S Zhou
- Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
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Ueland BG, Pandey A, Lee Y, Sapkota A, Choi Y, Haskel D, Rosenberg RA, Lang JC, Harmon BN, Johnston DC, Kreyssig A, Goldman AI. Itinerant ferromagnetism in the As 4p conduction band of Ba_{0.6}K_{0.4}Mn_{2}As_{2} identified by X-ray magnetic circular dichroism. Phys Rev Lett 2015; 114:217001. [PMID: 26066451 DOI: 10.1103/physrevlett.114.217001] [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] [Received: 11/30/2014] [Indexed: 06/04/2023]
Abstract
X-ray magnetic circular dichroism (XMCD) measurements on single-crystal and powder samples of Ba_{0.6}K_{0.4}Mn_{2}As_{2} show that the ferromagnetism below T_{C}≈100 K arises in the As 4p conduction band. No XMCD signal is observed at the Mn x-ray absorption edges. Below T_{C}, however, a clear XMCD signal is found at the As K edge which increases with decreasing temperature. The XMCD signal is absent in data taken with the beam directed parallel to the crystallographic c axis indicating that the orbital magnetic moment lies in the basal plane of the tetragonal lattice. These results show that the previously reported itinerant ferromagnetism is associated with the As 4p conduction band and that distinct local-moment antiferromagnetism and itinerant ferromagnetism with perpendicular easy axes coexist in this compound at low temperature.
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Affiliation(s)
- B G Ueland
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Abhishek Pandey
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Y Lee
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - A Sapkota
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - Y Choi
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - R A Rosenberg
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J C Lang
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - B N Harmon
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - D C Johnston
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - A Kreyssig
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - A I Goldman
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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Takayama T, Kato A, Dinnebier R, Nuss J, Kono H, Veiga LSI, Fabbris G, Haskel D, Takagi H. Hyperhoneycomb Iridate β-Li2IrO3 as a platform for Kitaev magnetism. Phys Rev Lett 2015; 114:077202. [PMID: 25763972 DOI: 10.1103/physrevlett.114.077202] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Indexed: 06/04/2023]
Abstract
A complex iridium oxide β-Li(2)IrO(3) crystallizes in a hyperhoneycomb structure, a three-dimensional analogue of honeycomb lattice, and is found to be a spin-orbital Mott insulator with J(eff)=1/2 moment. Ir ions are connected to the three neighboring Ir ions via Ir-O(2)-Ir bonding planes, which very likely gives rise to bond-dependent ferromagnetic interactions between the J(eff)=1/2 moments, an essential ingredient of Kitaev model with a spin liquid ground state. Dominant ferromagnetic interaction between J(eff)=1/2 moments is indeed confirmed by the temperature dependence of magnetic susceptibility χ(T) which shows a positive Curie-Weiss temperature θ(CW)∼+40 K. A magnetic ordering with a very small entropy change, likely associated with a noncollinear arrangement of J(eff)=1/2 moments, is observed at T(c)=38 K. With the application of magnetic field to the ordered state, a large moment of more than 0.35 μ(B)/Ir is induced above 3 T, a substantially polarized J(eff)=1/2 state. We argue that the close proximity to ferromagnetism and the presence of large fluctuations evidence that the ground state of hyperhoneycomb β-Li(2)IrO(3) is located in close proximity of a Kitaev spin liquid.
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Affiliation(s)
- T Takayama
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
- Department of Physics and Department of Advanced Materials, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - A Kato
- Department of Physics and Department of Advanced Materials, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - R Dinnebier
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - J Nuss
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - H Kono
- Department of Physics and Department of Advanced Materials, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - L S I Veiga
- Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, Campinas, São Paulo 13083-859, Brazil
- Laboratório Nacional de Luz Síncrotron, Campinas, São Paulo 13083-970, Brazil
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - G Fabbris
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - H Takagi
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
- Department of Physics and Department of Advanced Materials, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
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Haskel D, Fabbris G, Zhernenkov M, Kong PP, Jin CQ, Cao G, van Veenendaal M. Pressure tuning of the spin-orbit coupled ground state in Sr2IrO4. Phys Rev Lett 2012; 109:027204. [PMID: 23030204 DOI: 10.1103/physrevlett.109.027204] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Indexed: 06/01/2023]
Abstract
X-ray absorption spectroscopy studies of the magnetic-insulating ground state of Sr2IrO4 at ambient pressure show a clear deviation from a strong spin-orbit (SO) limit J(eff)=1/2 state, a result of local exchange interactions and a nonzero tetragonal crystal field mixing SO split J(eff)=1/2, 3/2 states. X-ray magnetic circular dichroism measurements in a diamond anvil cell show a magnetic transition at a pressure of ∼17 GPa, where the "weak" ferromagnetic moment is quenched despite transport measurements showing insulating behavior to at least 40 GPa. The magnetic transition has implications for the origin of the insulating gap and the nature of exchange interactions in this SO coupled system. The expectation value of the angular part of the SO interaction, <L·S>, extrapolates to zero at ∼80-90 GPa where an increased bandwidth strongly mixes J(eff)=1/2, 3/2 states and SO interactions no longer dominate the electronic ground state of Sr2IrO4.
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Affiliation(s)
- D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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14
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Souza-Neto NM, Zhao J, Alp EE, Shen G, Sinogeikin SV, Lapertot G, Haskel D. Reentrant valence transition in EuO at high pressures: beyond the bond-valence model. Phys Rev Lett 2012; 109:026403. [PMID: 23030187 DOI: 10.1103/physrevlett.109.026403] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Indexed: 06/01/2023]
Abstract
The pressure-dependent relation between Eu valence and lattice structure in model compound EuO is studied with synchrotron-based x-ray spectroscopic and diffraction techniques. Contrary to expectation, a 7% volume collapse at ≈45 GPa is accompanied by a reentrant Eu valence transition into a lower valence state. In addition to highlighting the need for probing both structure and electronic states directly when valence information is sought in mixed-valent systems, the results also show that widely used bond-valence methods fail to quantitatively describe the complex electronic valence behavior of EuO under pressure.
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Affiliation(s)
- N M Souza-Neto
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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15
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Alonso J, Fdez-Gubieda ML, Sarmiento G, Chaboy J, Boada R, García Prieto A, Haskel D, Laguna-Marco MA, Lang JC, Meneghini C, Fernández Barquín L, Neisius T, Orue I. Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys. Nanotechnology 2012; 23:025705. [PMID: 22166763 DOI: 10.1088/0957-4484/23/2/025705] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe50Ag50 and Fe55Ag45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2–4 nm) nanoparticles and fcc Ag (10–12 nm) nanoparticles, separated by an amorphous Fe50Ag50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling.
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Affiliation(s)
- J Alonso
- Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), Campus de Leioa, 48940 Leioa, Spain
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16
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Laguna-Marco MA, Haskel D, Souza-Neto N, Lang JC, Krishnamurthy VV, Chikara S, Cao G, van Veenendaal M. Orbital magnetism and spin-orbit effects in the electronic structure of BaIrO3. Phys Rev Lett 2010; 105:216407. [PMID: 21231332 DOI: 10.1103/physrevlett.105.216407] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Indexed: 05/30/2023]
Abstract
The electronic structure and magnetism of Ir 5d5 states in nonmetallic, weakly ferromagnetic BaIrO3 are probed with x-ray absorption techniques. Contrary to expectation, the Ir 5d orbital moment is found to be ~1.5 times larger than the spin moment. This unusual, atomiclike nature of the 5d moment is driven by a strong spin-orbit interaction in heavy Ir ions, as confirmed by the nonstatistical large branching ratio at Ir L(2,3) absorption edges. As a consequence, orbital interactions cannot be neglected when addressing the nature of magnetic ordering in BaIrO3. The local moment behavior persists even as the metallic-paramagnetic phase boundary is approached with Sr doping or applied pressure.
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Affiliation(s)
- M A Laguna-Marco
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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17
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de la Venta J, Bouzas V, Pucci A, Laguna-Marco MA, Haskel D, te Velthuis SGE, Hoffmann A, Lal J, Bleuel M, Ruggeri G, de Julián Fernández C, García MA. X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles. J Nanosci Nanotechnol 2009; 9:6434-6438. [PMID: 19908546 DOI: 10.1166/jnn.2009.1877] [Citation(s) in RCA: 6] [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] [Indexed: 05/28/2023]
Abstract
X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 x 10(-4) was found at the Au L3 edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M(S), of 0.06 emu/g(Au). SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.
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Affiliation(s)
- J de la Venta
- Dpto. Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Nandi S, Kreyssig A, Tan L, Kim JW, Yan JQ, Lang JC, Haskel D, McQueeney RJ, Goldman AI. Nature of Ho magnetism in multiferroic HoMnO3. Phys Rev Lett 2008; 100:217201. [PMID: 18518629 DOI: 10.1103/physrevlett.100.217201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Indexed: 05/26/2023]
Abstract
Using x-ray resonant magnetic scattering and x-ray magnetic circular dichroism, techniques that are element specific, we have elucidated the role of Ho3+ in multiferroic HoMnO3. In zero field, Ho3+ orders antiferromagnetically with moments aligned along the hexagonal c direction below 40 K, and undergoes a transition to another magnetic structure below 4.5 K. In applied electric fields of up to 1 x 10(7) V/m, the magnetic structure of Ho3+ remains unchanged.
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Affiliation(s)
- S Nandi
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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Haskel D, Tseng YC, Lang JC, Sinogeikin S. Instrument for x-ray magnetic circular dichroism measurements at high pressures. Rev Sci Instrum 2007; 78:083904. [PMID: 17764332 DOI: 10.1063/1.2773800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
An instrument has been developed for x-ray magnetic circular dichroism (XMCD) measurements at high pressures and low temperatures. This instrument couples a nonmagnetic copper-beryllium diamond anvil cell featuring perforated diamonds with a helium flow cryostat and an electromagnet. The applied pressure can be controlled in situ using a gas membrane and calibrated using Cu K-edge x-ray absorption fine structure measurements. The performance of this instrument was tested by measuring the XMCD spectra of the Gd(5)Si(2)Ge(2) giant magnetocaloric material.
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Affiliation(s)
- D Haskel
- Magnetic Materials Group, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
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Haskel D, Lee YB, Harmon BN, Islam Z, Lang JC, Srajer G, Mudryk Y, Gschneidner KA, Pecharsky VK. Role of Ge in bridging ferromagnetism in the giant magnetocaloric Gd5(Ge1-xSix)4 alloys. Phys Rev Lett 2007; 98:247205. [PMID: 17677990 DOI: 10.1103/physrevlett.98.247205] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Indexed: 05/16/2023]
Abstract
X-ray magnetic circular dichroism (XMCD) measurements and density functional theory (DFT) are used to study the electronic conduction states in Gd5(Ge(1-x)Si(x))4 materials through the first-order bond-breaking magnetostructural transition responsible for their giant magnetocaloric effect. Spin-dependent hybridization between Ge 4p and Gd 5d conduction states, which XMCD senses through the induced magnetic polarization in Ge ions, enables long-range Ruderman-Kittel-Kasuya-Yosida ferromagnetic interactions between Gd 4f moments in adjacent Gd slabs connected by Ge(Si) bonds. These interactions are strong below but weaken above the Ge(Si) bond-breaking transition that destroys 3D ferromagnetic order.
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Affiliation(s)
- D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Krishnamurthy VV, Lang JC, Haskel D, Keavney DJ, Srajer G, Robertson JL, Sales BC, Mandrus DG, Singh DJ, Bilc DI. Ferrimagnetism in EuFe4Sb12 due to the interplay of f-electron moments and a nearly ferromagnetic host. Phys Rev Lett 2007; 98:126403. [PMID: 17501140 DOI: 10.1103/physrevlett.98.126403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Indexed: 05/15/2023]
Abstract
We combine x-ray magnetic circular dichroism spectroscopy at Fe L2,3 edges, at Eu M4,5 edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu0.95Fe4Sb12 is a ferrimagnet in which the Fe 3d moment and the Eu2+ 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L3 edge XAS, we find that about 13% of the Eu have a formal valence of 3+. We ascribe the origin of ferrimagnetism at a relatively high transition temperature TC of 85 K in Eu0.95Fe4Sb12 to f-electron interaction with the nearly ferromagnetic [Fe4Sb12]2.2- host lattice.
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Affiliation(s)
- V V Krishnamurthy
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Haskel D, Lang JC, Islam Z, Cady A, Srajer G, van Veenendaal M, Canfield PC. Atomic origin of magnetocrystalline anisotropy in Nd(2)Fe(14)B. Phys Rev Lett 2005; 95:217207. [PMID: 16384180 DOI: 10.1103/physrevlett.95.217207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Indexed: 05/05/2023]
Abstract
The magnetic moment reversal at each of the two inequivalent Nd sites in a single crystal of ferromagnetic Nd(2)Fe(14)B is probed by dichroic resonant diffraction of circularly polarized x rays. The results, supported by theory, show that the c-axis intrinsic magnetic stability of this superior permanent magnetic material arises predominantly at one of the Nd sites (g). The other site (f) undermines magnetic stability by favoring a magnetic moment orientation in the basal plane.
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Affiliation(s)
- D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Srajer G, Haskel D, Lang JC, Stevenson CK, Choi Y, Jiang JS, Bader SD. Magnetic imaging of biquadratic coupling in ferromagnetic bilayers. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305095577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Haskel D, Lang J, Islam Z, Cady A, Srajer G, Van Veenendaal M, Canfield P, Ankudinov A. Element- and site-specific study of the atomic origin of magnetic hardness in modern magnets. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305099241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Islam Z, Liu X, Sinha SK, Lang JC, Moss SC, Haskel D, Srajer G, Wochner P, Lee DR, Haeffner DR, Welp U. Four-unit-cell superstructure in the optimally doped YBa2Cu3O6.92 superconductor. Phys Rev Lett 2004; 93:157008. [PMID: 15524931 DOI: 10.1103/physrevlett.93.157008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Indexed: 05/24/2023]
Abstract
Diffuse x-ray scattering measurements reveal that the optimally doped YBa2Cu3O6.92 superconductor is intrinsically modulated due to the formation of a kinetically limited 4-unit-cell superlattice, q(0)=(1/4, 0, 0), along the shorter Cu-Cu bonds. The superlattice consists of large anisotropic displacements of Cu, Ba, and O atoms, respectively, which are correlated over approximately 3-6 unit cells in the ab plane, and appears to be consistent with the presence of an O-ordered "ortho-IV" phase. Long-range strains emanating from these modulated regions generate an inhomogeneous lattice which may play a fundamentally important role in the electronic properties of yttrium-barium-copper-oxides.
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Affiliation(s)
- Zahirul Islam
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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Gilbert B, Frazer BH, Belz A, Conrad PG, Nealson KH, Haskel D, Lang JC, Srajer G, De Stasio G. Multiple Scattering Calculations of Bonding and X-ray Absorption Spectroscopy of Manganese Oxides. J Phys Chem A 2003. [DOI: 10.1021/jp021493s] [Citation(s) in RCA: 232] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- B. Gilbert
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - B. H. Frazer
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - A. Belz
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - P. G. Conrad
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - K. H. Nealson
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - D. Haskel
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - J. C. Lang
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - G. Srajer
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
| | - G. De Stasio
- Department of Physics, and Synchrotron Radiation Center, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589, Institut de Physique Appliquee, Ecole Polytechnique Federal de Lausanne, Jet Propulsion Laboratory, Pasedena, California, and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439
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Haskel D, Srajer G, Lang JC, Pollmann J, Nelson CS, Jiang JS, Bader SD. Enhanced interfacial magnetic coupling of Gd /Fe multilayers. Phys Rev Lett 2001; 87:207201. [PMID: 11690506 DOI: 10.1103/physrevlett.87.207201] [Citation(s) in RCA: 9] [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: 08/02/2001] [Indexed: 05/23/2023]
Abstract
The spatial extent zeta(AFM) and strength J(AFM) of the antiferromagnetic (AFM) exchange coupling at buried Gd /Fe interfaces in ferrimagnetic [Gd(50 A)Fe(15,35 A)](15) sputtered multilayers is obtained from combined x-ray resonance magnetic reflectivity and magnetic circular dichroism measurements. zeta(AFM) is 4.1(7) A or approximately 1-2 interatomic distances in bulk Gd and Fe; J(AFM) is 1050(90) K, comparable to the ferromagnetic exchange in bulk Fe.
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Affiliation(s)
- D Haskel
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Haskel D, Stern EA, Dogan F, Moodenbaugh AR. Dopant structural distortions in high-temperature superconductors: anactive or a passive role? J Synchrotron Radiat 2001; 8:186-190. [PMID: 11512722 DOI: 10.1107/s090904950001846x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 11/23/2000] [Indexed: 05/23/2023]
Abstract
The parent compounds of high-temperature superconductors, such as YBa2Cu3O6 and La2CuO4, are strongly interacting electron systems, rendering them insulators with Mott-Hubbard gaps of a few electronvolts. Charge carriers (holes) are introduced by chemical doping, causing an insulator-metal (IM) transition and, at low temperatures, superconductivity. The role of dopants is widely seen as limited to the introduction of holes into the CuO2 planes (i.e. occupying electronic states derived from Cu 3d(x2-y2) and O 2p(x,y) atomic orbitals). Most theories of high-Tc superconductivity deal with pairing interactions between these planar holes. Local distortions around dopants are poorly understood, because of the experimental difficulty in obtaining such information, particularly at low doping. This has resulted in the neglect, in most theories, of the effect of such distortions on the chemical and electronic structure of high-Tc superconductors. Angular-resolved X-ray absorption fine structure (XAFS) spectroscopy on oriented samples is an ideal technique to elucidate the dopant distortions. Element specificity, together with a large orientation dependence of the XAFS signal in these layered structures, allows the local structure around dopants to be resolved. Results are presented here on (Sr, Ba) and Ni dopants, which substitute at the La and Cu sites, respectively, of insulating La2CuO4. The relevance of the measured local distortions for a complete understanding of the normal and superconducting properties of cuprates is discussed.
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Affiliation(s)
- D Haskel
- Experimental Facilities Division, Advanced Photon Source, Argonne National Laboratory, IL 60439, USA.
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Haskel D, Stern EA, Dogan F, Moodenbaugh AR. Structural disorder and the origin of high-Tc suppression in La1.875Ba0.125CuO4. J Synchrotron Radiat 1999; 6:755-757. [PMID: 15263448 DOI: 10.1107/s0909049599001478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 01/26/1999] [Indexed: 05/24/2023]
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Haskel D, Stern EA, Polinger V, Dogan F. Why does Ni suppress superconductivity in La1.85Sr0.15Cu1-yNiyO4? J Synchrotron Radiat 1999; 6:758-760. [PMID: 15263449 DOI: 10.1107/s090904959900148x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 01/26/1999] [Indexed: 05/24/2023]
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Stern EA, Polinger VZ, Haskel D. Electronic states of doped holes in La(2-x)SrxCuO4: a unique application of XAFS. J Synchrotron Radiat 1999; 6:373-375. [PMID: 15263312 DOI: 10.1107/s0909049599001405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 01/26/1999] [Indexed: 05/24/2023]
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Haskel D, Stern EA, Hinks DG, Mitchell AW, Jorgensen JD, Budnick JI. Dopant and temperature induced structural phase transitions in La2-xSrxCuO4. Phys Rev Lett 1996; 76:439-442. [PMID: 10061457 DOI: 10.1103/physrevlett.76.439] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Haskel D, Shechter H, Stern EA, Newville M, Yacoby Y. Anomalous temperature behavior of Sn impurities. Phys Rev B Condens Matter 1993; 47:14032-14043. [PMID: 10005742 DOI: 10.1103/physrevb.47.14032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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