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Hiraishi M, Okabe H, Koda A, Kadono R, Muroi T, Hirai D, Hiroi Z. Nonmagnetic Ground State in RuO_{2} Revealed by Muon Spin Rotation. Phys Rev Lett 2024; 132:166702. [PMID: 38701457 DOI: 10.1103/physrevlett.132.166702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 03/07/2024] [Accepted: 03/14/2024] [Indexed: 05/05/2024]
Abstract
The magnetic ground state of single crystalline RuO_{2} was investigated by the muon spin rotation and relaxation (μSR) experiment. The spin precession signal due to the spontaneous internal magnetic field B_{loc}, which is expected in the magnetically ordered phase, was not observed in the temperature range 5-400 K. Muon sites were evaluated by first-principles calculations using dilute hydrogen simulating muon as pseudohydrogen, and B_{loc} was simulated for the antiferromagnetic structures with a Ru magnetic moment |m_{Ru}|≈0.05μ_{B} suggested from diffraction experiments. As a result, the possibility was ruled out that muons are localized at sites where B_{loc} accidentally cancels. Conversely, assuming that the slow relaxation observed in μSR spectra was part of the precession signal, the upper limit for the magnitude of |m_{Ru}| was estimated to be 4.8(2)×10^{-4}μ_{B}, which is significantly less than 0.05μ_{B}. These results indicate that the antiferromagnetic order, as reported, is unlikely to exist in the bulk crystal.
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Affiliation(s)
- M Hiraishi
- Graduate School of Science and Engineering, Ibaraki University, Mito, Ibaraki 310-8512, Japan
- Muon Science Laboratory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - H Okabe
- Muon Science Laboratory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
- Institute for Materials Research, Tohoku University (IMR), Aoba-ku, Sendai 980-8577, Japan
| | - A Koda
- Muon Science Laboratory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
- Graduate University for Advanced Studies, SOKENDAI
| | - R Kadono
- Muon Science Laboratory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - T Muroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - D Hirai
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Z Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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2
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Zvyagin SA, Ponomaryov AN, Wosnitza J, Hirai D, Hiroi Z, Gen M, Kohama Y, Matsuo A, Matsuda YH, Kindo K. Dimensional reduction and incommensurate dynamic correlations in the [Formula: see text] triangular-lattice antiferromagnet Ca 3ReO 5Cl 2. Nat Commun 2022; 13:6310. [PMID: 36274086 PMCID: PMC9588769 DOI: 10.1038/s41467-022-33992-5] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/07/2022] [Indexed: 12/03/2022] Open
Abstract
The observation of spinon excitations in the [Formula: see text] triangular antiferromagnet Ca3ReO5Cl2 reveals a quasi-one-dimensional (1D) nature of magnetic correlations, in spite of the nominally 2D magnetic structure. This phenomenon is known as frustration-induced dimensional reduction. Here, we present high-field electron spin resonance spectroscopy and magnetization studies of Ca3ReO5Cl2, allowing us not only to refine spin-Hamiltonian parameters, but also to investigate peculiarities of its low-energy spin dynamics. We argue that the presence of the uniform Dzyaloshinskii-Moriya interaction (DMI) shifts the spinon continuum in momentum space and, as a result, opens a zero-field gap at the Γ point. We observed this gap directly. The shift is found to be consistent with the structural modulation in the ordered state, suggesting this material as a perfect model triangular-lattice system, where a pure DMI-spiral ground state can be realized.
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Affiliation(s)
- S. A. Zvyagin
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - A. N. Ponomaryov
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Present Address: Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - J. Wosnitza
- Dresden High Magnetic Field Laboratory (HLD-EMFL) and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
- Institut für Festkörper- und Materialphysik, TU Dresden, 01062 Dresden, Germany
| | - D. Hirai
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - Z. Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - M. Gen
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - Y. Kohama
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - A. Matsuo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - Y. H. Matsuda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
| | - K. Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 Japan
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3
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Okuma R, Nakamura D, Okubo T, Miyake A, Matsuo A, Kindo K, Tokunaga M, Kawashima N, Takeyama S, Hiroi Z. A series of magnon crystals appearing under ultrahigh magnetic fields in a kagomé antiferromagnet. Nat Commun 2019; 10:1229. [PMID: 30874548 PMCID: PMC6420565 DOI: 10.1038/s41467-019-09063-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 02/13/2019] [Indexed: 11/30/2022] Open
Abstract
Geometrical frustration and a high magnetic field are two key factors for realizing unconventional quantum states in magnetic materials. Specifically, conventional magnetic order can potentially be destroyed by competing interactions and may be replaced by an exotic state that is characterized in terms of quasiparticles called magnons, the density and chemical potential of which are controlled by the magnetic field. Here we show that a synthetic copper mineral, Cd-kapellasite, which comprises a kagomé lattice consisting of corner-sharing triangles of spin-1/2 Cu2+ ions, exhibits an unprecedented series of fractional magnetization plateaus in ultrahigh magnetic fields of up to 160 T. We propose that these quantum states can be interpreted as crystallizations of emergent magnons localized on the hexagon of the kagomé lattice.
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Affiliation(s)
- R Okuma
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan.
| | - D Nakamura
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - T Okubo
- Department of Physics, The University of Tokyo, Tokyo, 113-0033, Japan
| | - A Miyake
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - A Matsuo
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - K Kindo
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - M Tokunaga
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - N Kawashima
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - S Takeyama
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Z Hiroi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
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4
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Nguyen TMH, Sandilands LJ, Sohn CH, Kim CH, Wysocki AL, Yang IS, Moon SJ, Ko JH, Yamaura J, Hiroi Z, Noh TW. Author Correction: Two-magnon scattering in the 5d all-in-all-out pyrochlore magnet Cd 2Os 2O 7. Nat Commun 2017; 8:1702. [PMID: 29150597 PMCID: PMC5693863 DOI: 10.1038/s41467-017-01513-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A correction to this article has been published and is linked from the HTML version of this article.
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Affiliation(s)
- Thi Minh Hien Nguyen
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - Luke J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea.,Measurement Science and Standards, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
| | - C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | | | - In-Sang Yang
- Department of Physics and Division of Nano-Sciences, Ewha Womans University, Seoul, 120-750, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul, 133-791, Republic of Korea
| | - Jae-Hyeon Ko
- Department of Physics, Hallym University, Chuncheon, Gangwondo, 24252, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa, 226-8503, Japan
| | - Z Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea. .,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea.
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Matsuura K, Mizukami Y, Arai Y, Sugimura Y, Maejima N, Machida A, Watanuki T, Fukuda T, Yajima T, Hiroi Z, Yip KY, Chan YC, Niu Q, Hosoi S, Ishida K, Mukasa K, Kasahara S, Cheng JG, Goh SK, Matsuda Y, Uwatoko Y, Shibauchi T. Maximizing T c by tuning nematicity and magnetism in FeSe 1-x S x superconductors. Nat Commun 2017; 8:1143. [PMID: 29070845 PMCID: PMC5656606 DOI: 10.1038/s41467-017-01277-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [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: 04/27/2017] [Accepted: 09/04/2017] [Indexed: 11/13/2022] Open
Abstract
A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature (T c). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving non-magnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe have considerable overlap, how each order affects superconductivity remains perplexing. Here we construct the three-dimensional electronic phase diagram, temperature (T) against pressure (P) and isovalent S-substitution (x), for FeSe1-x S x . By simultaneously tuning chemical and physical pressures, against which the chalcogen height shows a contrasting variation, we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended non-magnetic tetragonal phase emerges, where T c shows a striking enhancement. The completed phase diagram uncovers that high-T c superconductivity lies near both ends of the dome-shaped antiferromagnetic phase, whereas T c remains low near the nematic critical point.
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Affiliation(s)
- K Matsuura
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Y Mizukami
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Y Arai
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Y Sugimura
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - N Maejima
- Synchrotron Radiation Research Center, National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo, 679-5148, Japan
| | - A Machida
- Synchrotron Radiation Research Center, National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo, 679-5148, Japan
| | - T Watanuki
- Synchrotron Radiation Research Center, National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo, 679-5148, Japan
| | - T Fukuda
- Materials Sciences Research Center, Japan Atomic Energy Agency (SPring-8/JAEA), Sayo, Hyogo, 679-5148, Japan
| | - T Yajima
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Z Hiroi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - K Y Yip
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Y C Chan
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Q Niu
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - S Hosoi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - K Ishida
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - K Mukasa
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - S Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China
| | - S K Goh
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Y Matsuda
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Y Uwatoko
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan.
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6
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Wawrzyńczak R, Tanaka Y, Yoshida M, Okamoto Y, Manuel P, Casati N, Hiroi Z, Takigawa M, Nilsen GJ. Classical Spin Nematic Transition in LiGa_{0.95}In_{0.05}Cr_{4}O_{8}. Phys Rev Lett 2017; 119:087201. [PMID: 28952772 DOI: 10.1103/physrevlett.119.087201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 06/07/2023]
Abstract
We present the results of a combined ^{7}Li-NMR and diffraction study on LiGa_{0.95}In_{0.05}Cr_{4}O_{8}, a member of the LiGa_{1-x}In_{x}Cr_{4}O_{8} "breathing" pyrochlore family. Via specific heat and NMR measurements, we find that the complex sequence of first-order transitions observed for LiGaCr_{4}O_{8} is replaced by a single second-order transition at T_{f}=11 K. Neutron and x-ray diffraction rule out both structural symmetry lowering and magnetic long-range order as the origin of this transition. Instead, reverse Monte Carlo fitting of the magnetic diffuse scattering indicates that the low-temperature phase may be described as a collinear spin nematic state, characterized by a quadrupolar order parameter. This state also shows signs of short-range order between collinear spin arrangements on tetrahedra, revealed by mapping the reverse Monte Carlo spin configurations onto a three-state color model.
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Affiliation(s)
- R Wawrzyńczak
- Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France
| | - Y Tanaka
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - M Yoshida
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Y Okamoto
- Department of Applied Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - P Manuel
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
| | - N Casati
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Z Hiroi
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - M Takigawa
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - G J Nilsen
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
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7
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Nguyen TMH, Sandilands LJ, Sohn CH, Kim CH, Wysocki AL, Yang IS, Moon SJ, Ko JH, Yamaura J, Hiroi Z, Noh TW. Two-magnon scattering in the 5d all-in-all-out pyrochlore magnet Cd 2Os 2O 7. Nat Commun 2017; 8:251. [PMID: 28811471 PMCID: PMC5557926 DOI: 10.1038/s41467-017-00228-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 06/12/2017] [Indexed: 11/17/2022] Open
Abstract
5d pyrochlore oxides with all-in-all-out magnetic order are prime candidates for realizing strongly correlated, topological phases of matter. Despite significant effort, a full understanding of all-in-all-out magnetism remains elusive as the associated magnetic excitations have proven difficult to access with conventional techniques. Here we report a Raman spectroscopy study of spin dynamics in the all-in-all-out magnetic state of the 5d pyrochlore Cd2Os2O7. Through a comparison between the two-magnon scattering and spin-wave theory, we confirm the large single ion anisotropy in this material and show that the Dzyaloshinskii-Moriya and exchange interactions play a significant role in the spin-wave dispersions. The Raman data also reveal complex spin-charge-lattice coupling and indicate that the metal-insulator transition in Cd2Os2O7 is Lifshitz-type. Our work establishes Raman scattering as a simple and powerful method for exploring the spin dynamics in 5d pyrochlore magnets.Pyrochlore 5d transition metal oxides are expected to have interesting forms of magnetic order but are hard to study with conventional probes. Here the authors show that Raman scattering can be used to measure magnetic excitations in Cd2Os2O7 and that it exhibits complex spin-charge-lattice coupling.
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Affiliation(s)
- Thi Minh Hien Nguyen
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - Luke J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
- Measurement Science and Standards, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
| | - C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea
| | | | - In-Sang Yang
- Department of Physics and Division of Nano-Sciences, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea
| | - Jae-Hyeon Ko
- Department of Physics, Hallym University, Chuncheon, Gangwondo, 24252, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa, 226-8503, Japan
| | - Z Hiroi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 151-742, Republic of Korea.
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 151-742, Republic of Korea.
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8
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Sohn CH, Kim CH, Sandilands LJ, Hien NTM, Kim SY, Park HJ, Kim KW, Moon SJ, Yamaura J, Hiroi Z, Noh TW. Strong Spin-Phonon Coupling Mediated by Single Ion Anisotropy in the All-In-All-Out Pyrochlore Magnet Cd_{2}Os_{2}O_{7}. Phys Rev Lett 2017; 118:117201. [PMID: 28368646 DOI: 10.1103/physrevlett.118.117201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Indexed: 06/07/2023]
Abstract
Spin-phonon coupling mediated by single ion anisotropy was investigated using optical spectroscopy and first-principles calculations in the all-in-all-out pyrochlore magnet Cd_{2}Os_{2}O_{7}. Clear anomalies were observed in both the phonon frequencies and linewidths at the magnetic ordering temperature. The renormalization of the phonon modes was exceptionally large, signifying the presence of an unconventional magnetoelastic term from large spin-orbit coupling. In addition, the relative phonon frequency shifts show a strong correlation with the modulation of noncubic crystal field by the corresponding lattice distortion. Our observation establishes a new type of spin-phonon coupling through single ion anisotropy, a second-order spin-orbit coupling term, in Cd_{2}Os_{2}O_{7}.
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Affiliation(s)
- C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - C H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - L J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - N T M Hien
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - S Y Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - H J Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 133-791, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - Z Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
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9
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Sohn CH, Jeong H, Jin H, Kim S, Sandilands LJ, Park HJ, Kim KW, Moon SJ, Cho DY, Yamaura J, Hiroi Z, Noh TW. Optical Spectroscopic Studies of the Metal-Insulator Transition Driven by All-In-All-Out Magnetic Ordering in 5d Pyrochlore Cd(2)Os(2)O(7). Phys Rev Lett 2015; 115:266402. [PMID: 26765010 DOI: 10.1103/physrevlett.115.266402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Indexed: 06/05/2023]
Abstract
We investigated the metal-insulator transition (MIT) driven by all-in-all-out (AIAO) antiferromagnetic ordering in the 5d pyrochlore Cd(2)Os(2)O(7) using optical spectroscopy and first-principles calculations. We showed that the temperature evolution in the band-gap edge and free carrier density were consistent with rigid upward (downward) shifts of electron (hole) bands, similar to the case of Lifshitz transitions. The delicate relationship between the band gap and free carrier density provides experimental evidence for the presence of an AIAO metallic phase, a natural consequence of such MITs. The associated spectral weight change at high energy and first-principles calculations further support the origin of the MIT from the band shift near the Fermi level. Our data consistently support that the MIT induced by AIAO ordering in Cd(2)Os(2)O(7) is not close to a Slater type but instead to a Lifshitz type.
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Affiliation(s)
- C H Sohn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Hogyun Jeong
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Hosub Jin
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Soyeon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - L J Sandilands
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - H J Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - S J Moon
- Department of Physics, Hanyang University, Seoul 04763, Republic of Korea
| | - Deok-Yong Cho
- Department of Physics, Chonbuk National University, Jeonju 54896, Republic of Korea
| | - J Yamaura
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - Z Hiroi
- ISSP, University of Tokyo, Kashiwa 277-8581, Japan
| | - T W Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
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10
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Kudo K, Takasuga M, Okamoto Y, Hiroi Z, Nohara M. Giant phonon softening and enhancement of superconductivity by phosphorus doping of BaNi2As2. Phys Rev Lett 2012; 109:097002. [PMID: 23002873 DOI: 10.1103/physrevlett.109.097002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Indexed: 05/05/2023]
Abstract
The effects of phosphorus doping on the structural and superconducting phase transitions of BaNi2(As(1-x)P(x))2 were studied. The specific heat, resistivity, and magnetic susceptibility were measured. The results revealed an abrupt increase in the superconducting transition temperature (T(c)) from 0.6 K in the triclinic phase (space group P1¯) with less phosphorus (x≤0.067) to 3.3 K in the tetragonal phase (space group I4/mmm) with more phosphorus (x≥0.067). Our data analysis suggests that a doping-induced softening related to an in-plane Ni and As(P) phonon mode is responsible for the enhanced superconductivity in the tetragonal phase.
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Affiliation(s)
- K Kudo
- Department of Physics, Okayama University, Okayama 700-8530, Japan.
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11
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Yamaura J, Ohgushi K, Ohsumi H, Hasegawa T, Yamauchi I, Sugimoto K, Takeshita S, Tokuda A, Takata M, Udagawa M, Takigawa M, Harima H, Arima T, Hiroi Z. Tetrahedral magnetic order and the metal-insulator transition in the pyrochlore lattice of Cd2Os2O7. Phys Rev Lett 2012; 108:247205. [PMID: 23004317 DOI: 10.1103/physrevlett.108.247205] [Citation(s) in RCA: 14] [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: 11/26/2011] [Indexed: 06/01/2023]
Abstract
Cd2Os2O7 shows a peculiar metal-insulator transition at 227 K with magnetic ordering in a frustrated pyrochlore lattice, but its magnetic structure in the ordered state and the transition origin are yet uncovered. We observed a commensurate magnetic peak by resonant x-ray scattering in a high-quality single crystal. X-ray diffraction and Raman scattering experiments confirmed that the transition is not accompanied with any spatial symmetry breaking. We propose a noncollinear all-in-all-out spin arrangement on the tetrahedral network made of Os atoms. Based on this we suggest that the transition is not caused by the Slater mechanism as believed earlier but by an alternative mechanism related to the formation of the specific tetrahedral magnetic order on the pyrochlore lattice in the presence of strong spin-orbit interactions.
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Affiliation(s)
- J Yamaura
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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12
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Wulferding D, Lemmens P, Yoshida H, Okamoto Y, Hiroi Z. The spin dynamics in distorted kagome lattices: a comparative Raman study. J Phys Condens Matter 2012; 24:185602. [PMID: 22508934 DOI: 10.1088/0953-8984/24/18/185602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Despite the conceptional importance of realizing spin liquids in solid states only few compounds are known. On the other hand the effect of lattice distortions and anisotropies on the magnetic exchange topology and the fluctuation spectrum is an interesting problem. We compare the excitation spectra of the two s = 1/2 kagome lattice compounds, volborthite and vesignieite, using Raman scattering. We demonstrate that even small modifications of the crystal structure may have a huge effect on the phonon spectrum and low-temperature properties.
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Affiliation(s)
- D Wulferding
- Institute for Condensed Matter Physics, Technical University of Braunschweig, D-38106 Braunschweig, Germany.
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13
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Yoshida M, Takigawa M, Yoshida H, Okamoto Y, Hiroi Z. Phase diagram and spin dynamics in volborthite with a distorted kagome lattice. Phys Rev Lett 2009; 103:077207. [PMID: 19792685 DOI: 10.1103/physrevlett.103.077207] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Indexed: 05/28/2023]
Abstract
We report a (51)V-NMR study on a high-quality powder sample of volborthite Cu3V2O7(OH)2 . 2H2O, a spin-1/2 Heisenberg antiferromagnet on a distorted kagome lattice formed by isosceles triangles. In the magnetic fields below 4.5 T, a sharp peak in the nuclear spin-lattice relaxation rate 1/T(1) accompanied with line broadening revealed a magnetic transition near 1 K. The low temperature phase shows anomalies such as a Lorentzian line shape, a 1/T(1) proportional, variantT behavior indicating dense low-energy excitations, and a large spin-echo decay rate 1/T(2) pointing to unusually slow fluctuations. Another magnetic phase appears above 4.5 T with less anomalous spectral shape and dynamics.
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Affiliation(s)
- M Yoshida
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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14
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15
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Matsuhira K, Sekine C, Paulsen C, Wakeshima M, Hinatsu Y, Kitazawa T, Kiuchi Y, Hiroi Z, Takagi S. Spin freezing in the pyrochlore antiferromagnet Pr2Zr2O7. ACTA ACUST UNITED AC 2009. [DOI: 10.1088/1742-6596/145/1/012031] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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Yamaura J, Hiroi Z. Structural study on the rattling phenomena in the β-pyrochlore oxides and filled skutterudites. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308083682] [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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17
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Shibauchi T, Konczykowski M, van der Beek CJ, Okazaki R, Matsuda Y, Yamaura J, Nagao Y, Hiroi Z. Vortex redistribution below the first-order transition temperature in the beta-pyrochlore superconductor KOs2O6. Phys Rev Lett 2007; 99:257001. [PMID: 18233548 DOI: 10.1103/physrevlett.99.257001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Indexed: 05/25/2023]
Abstract
A miniature Hall-sensor array was used to detect magnetic induction locally in the vortex states of the beta-pyrochlore superconductor KOs2O6. Below the first-order transition at T{p} approximately 8 K, which is associated with a change in the rattling motion of K ions, the lower critical field and the remanent magnetization both show a distinct decrease, suggesting that the electron-phonon coupling is weakened below the transition. At high magnetic fields, the local induction shows an unexpectedly large jump at T{p} whose sign changes with position inside the sample. Our results demonstrate a novel redistribution of vortices whose energy is reduced abruptly below the first-order transition at T{p}.
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Affiliation(s)
- T Shibauchi
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan and Laboratoire des Solides Irradiés, Ecole Polytechnique, 91128 Palaiseau Cedex, France
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18
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Shimojima T, Shibata Y, Ishizaka K, Kiss T, Chainani A, Yokoya T, Togashi T, Wang XY, Chen CT, Watanabe S, Yamaura J, Yonezawa S, Muraoka Y, Hiroi Z, Saitoh T, Shin S. Interplay of superconductivity and rattling phenomena in beta-pyrochlore KOs2O6 studied by photoemission spectroscopy. Phys Rev Lett 2007; 99:117003. [PMID: 17930463 DOI: 10.1103/physrevlett.99.117003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Indexed: 05/25/2023]
Abstract
The electronic structure near the Fermi level (EF) of the beta-pyrochlore superconductor KOs2O6 is studied using laser-excited ultrahigh-resolution photoemission spectroscopy. The superconducting gap clearly opens across the superconducting transition (Tc=9.6 K), with the strong electron-phonon coupling value of 2Delta(0)/k B Tc>or=4.56. A fitting analysis identifies clear anomalies at Tp=7.5 K in the temperature dependencies of the superconducting gap size and the quasiparticle relaxation lifetime. These anomalies and the fine spectral structures arising from phonons suggest that the existence of the rattling behavior of K ions significantly affects the superconductivity in KOs2O6.
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Affiliation(s)
- T Shimojima
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
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19
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Shimono Y, Shibauchi T, Kasahara Y, Kato T, Hashimoto K, Matsuda Y, Yamaura J, Nagao Y, Hiroi Z. effects of rattling phonons on the dynamics of quasiparticle excitation in the beta-pyrochlore KOs(2)O(6) Superconductor. Phys Rev Lett 2007; 98:257004. [PMID: 17678049 DOI: 10.1103/physrevlett.98.257004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Indexed: 05/16/2023]
Abstract
Microwave penetration depth lambda and surface resistance at 27 GHz are measured in high quality crystals of KOs(2)O(6). Firm evidence for fully gapped superconductivity is provided from lambda(T). Below the second transition at T(p) approximately 8 K, the superfluid density shows a steplike change with a suppression of effective critical temperature T(c). Concurrently, the extracted quasiparticle scattering time shows a steep enhancement, indicating a strong coupling between the anomalous rattling motion of K ions and quasiparticles. The results imply that the rattling phonons help to enhance superconductivity, and that K sites freeze to an ordered state with long quasiparticle mean free path below T(p).
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Affiliation(s)
- Y Shimono
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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20
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Bonalde I, Ribeiro R, Brämer-Escamilla W, Yamaura J, Nagao Y, Hiroi Z. Isotropically gapped strong-coupling superconductivity in the beta-pyrochlore KOs2O6: evidence from penetration depth measurements. Phys Rev Lett 2007; 98:227003. [PMID: 17677873 DOI: 10.1103/physrevlett.98.227003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2007] [Indexed: 05/16/2023]
Abstract
We report on measurements of the temperature dependence of the magnetic penetration depth down to 0.04 K in a high-quality sample of the beta-pyrochlore KOs2O6 (Tc=9.65 K) with a spin-frustrated lattice. We observe temperature-independent behavior below T approximately 0.3Tc, which is firm evidence for the presence of an isotropic superconducting gap in this material. In the whole temperature range the superfluid density is very well described, without the need of adjustable parameters, by a strong-coupling extension of the BCS model for an isotropic gap. Thus, the penetration depth results indicate that KOs2O6 is a strong-coupling superconductor with a fully developed energy gap. No effect of the second phase transition taking place at Tp=7.5 K was observed on the penetration depth, which suggests that the Cooper pairs remain unperturbed across this transition.
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Affiliation(s)
- I Bonalde
- Centro de Física, Instituto Venezolano de Investigaciones Científicas, Apartado 21874, Caracas 1020-A, Venezuela
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21
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Yoshida M, Arai K, Kaido R, Takigawa M, Yonezawa S, Muraoka Y, Hiroi Z. NMR observation of rattling phonons in the pyrochlore superconductor KOs2O6. Phys Rev Lett 2007; 98:197002. [PMID: 17677651 DOI: 10.1103/physrevlett.98.197002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Indexed: 05/16/2023]
Abstract
We report nuclear magnetic resonance studies on the beta-pyrochlore oxide superconductor KOs2O6. The nuclear relaxation at the K sites is entirely caused by fluctuations of the electric field gradient, which we ascribe to highly anharmonic low frequency oscillation (rattling) of K ions. A phenomenological analysis shows a crossover from overdamped to underdamped behavior of the rattling phonons with decreasing temperature and its sudden sharpening below the superconducting transition temperature T(c). Suppression of the Hebel-Slichter peak in the relaxation rate at the O sites below T(c) also indicates strong electron-phonon coupling.
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Affiliation(s)
- M Yoshida
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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22
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Tabata Y, Kadowaki H, Matsuhira K, Hiroi Z, Aso N, Ressouche E, Fåk B. Kagomé ice state in the dipolar spin ice Dy2Ti2O7. Phys Rev Lett 2006; 97:257205. [PMID: 17280389 DOI: 10.1103/physrevlett.97.257205] [Citation(s) in RCA: 9] [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: 07/13/2006] [Indexed: 05/13/2023]
Abstract
We have investigated the kagomé ice behavior of the dipolar spin-ice compound Dy2Ti2O7 in a magnetic field along a [111] direction using neutron scattering and Monte Carlo simulations. The spin correlations show that the kagomé ice behavior predicted for the nearest-neighbor interacting model, where the field induces dimensional reduction and spins are frustrated in each two-dimensional kagomé lattice, occurs in the dipole interacting system. The spins freeze at low temperatures within the macroscopically degenerate ground states of the nearest-neighbor model.
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Affiliation(s)
- Y Tabata
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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23
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Kasahara Y, Shimono Y, Shibauchi T, Matsuda Y, Yonezawa S, Muraoka Y, Hiroi Z. Thermal conductivity of the pyrochlore superconductor KOs2O6: strong electron correlations and fully gapped superconductivity. Phys Rev Lett 2006; 96:247004. [PMID: 16907273 DOI: 10.1103/physrevlett.96.247004] [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: 03/01/2006] [Indexed: 05/11/2023]
Abstract
To elucidate the nature of the superconducting ground state of the geometrically frustrated pyrochlore KOs2O6 (Tc=9.6 K), the thermal conductivity was measured down to low temperatures (approximately Tc/100). We found that the quasiparticle mean free path is strikingly enhanced below a transition at Tp=7.8 K, indicating enormous electron inelastic scattering in the normal state. In magnetic fields, the conduction at T-->0 K is nearly constant up to approximately 0.4Hc2, in contrast with the rapid growth expected for superconductors with an anisotropic gap. This unambiguously indicates a fully gapped superconductivity, in contrast with previous studies. These results highlight that KOs2O6 is unique among superconductors with strong electron correlations.
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Affiliation(s)
- Y Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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24
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Muramatsu T, Takeshita N, Terakura C, Takagi H, Tokura Y, Yonezawa S, Muraoka Y, Hiroi Z. Anomalous pressure dependence of the superconducting transition temperature of beta-pyrochlore AOs2O6 oxides. Phys Rev Lett 2005; 95:167004. [PMID: 16241835 DOI: 10.1103/physrevlett.95.167004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Indexed: 05/05/2023]
Abstract
High-pressure effects on the superconducting transitions of beta-pyrochlore oxide superconductors AOs(2)O(6) (A = Cs,Rb,K) are studied by measuring resistivity under high pressures up to 10 GPa. The superconducting transition temperature T(c) first increases with increasing pressure in every compound and then exhibits a broad maximum at 7.6 K (6 GPa), 8.2 K (2 GPa), and 10 K (0.6 GPa) for A = Cs, Rb, and K, respectively. Finally, the superconductivity is suppressed completely at a critical pressure near 7 GPa and 6 GPa for A = Rb and K and probably above 10 GPa for A = Cs. Characteristic changes in the coefficient A of the T(2) term in resistivity and residual resistivity are observed, both of which are synchronized with the corresponding change in T(c).
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Affiliation(s)
- T Muramatsu
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, Japan
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25
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Asakura D, Quilty JW, Takubo K, Hirata S, Mizokawa T, Muraoka Y, Hiroi Z. Photoemission study of YBa(2)Cu(3)O(y) thin films under light illumination. Phys Rev Lett 2004; 93:247006. [PMID: 15697853 DOI: 10.1103/physrevlett.93.247006] [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: 07/16/2004] [Indexed: 05/24/2023]
Abstract
Heterojunctions of Nb-doped SrTiO3 substrate and YBa(2)Cu(3)O(y) thin films show photoconductivity and photovoltaic effects due to photocarrier injection. Photocarrier injection is expected to be a new carrier doping method in strongly correlated systems instead of chemical substitution. We have studied the nature of photocarrier injection in YBa(2)Cu(3)O(y)/SrTiO(3):Nb using x-ray photoemission spectroscopy with pulsed laser excitation. The core-level spectra shift to higher binding energy by 0.78 eV under pulsed laser illumination at 30 Hz. The energy shift corresponds to the photovoltage, which arises at the interface. In addition, we have observed that the energy shift strongly depends on the frequency of the laser. The lifetime of the injected photoholes has been estimated to be 40 ms by analyzing the frequency dependence.
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Affiliation(s)
- D Asakura
- Department of Complexity Science and Engineering and Department of Physics, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
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26
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Fukaya A, Fudamoto Y, Gat IM, Ito T, Larkin MI, Savici AT, Uemura YJ, Kyriakou PP, Luke GM, Rovers MT, Kojima KM, Keren A, Hanawa M, Hiroi Z. Muon spin relaxation and susceptibility studies of the pure and diluted spin 1/2 kagomé-like lattice system (CuxZn(1-x))3V2O7(OH2) 2H2O. Phys Rev Lett 2003; 91:207603. [PMID: 14683396 DOI: 10.1103/physrevlett.91.207603] [Citation(s) in RCA: 8] [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: 03/07/2003] [Indexed: 05/24/2023]
Abstract
Muon spin relaxation and magnetic susceptibility measurements have been performed on the pure and diluted spin 1/2 kagomé system (CuxZn(1-x))3V2O7(OH)2 2H2O. In the pure x=1 system we found a slowing down of Cu spin fluctuations with decreasing temperature towards T approximately 1 K, followed by slow and nearly temperature-independent spin fluctuations persisting down to T=50 mK, indicative of quantum fluctuations. No indication of static spin freezing was detected in either of the pure (x=1.0) or diluted samples. The observed magnitude of fluctuating fields indicates that the slow spin fluctuations represent an intrinsic property of kagomé network rather than impurity spins.
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Affiliation(s)
- A Fukaya
- Physics Department, Columbia University, 538 West 120th Street, New York, New York 10027, USA
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27
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Sakakibara T, Tayama T, Hiroi Z, Matsuhira K, Takagi S. Observation of a liquid-gas-type transition in the pyrochlore spin ice compound Dy2Ti2O7 in a magnetic field. Phys Rev Lett 2003; 90:207205. [PMID: 12785926 DOI: 10.1103/physrevlett.90.207205] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2002] [Indexed: 05/24/2023]
Abstract
Low temperature magnetization measurements on the pyrochlore spin ice compound Dy2Ti2O7 reveal that the ice-rule breaking spin flip, appearing at H approximately 0.9 T applied parallel to the [111] direction, turns into a novel first-order transition for T<0.36 K which is most probably of a liquid-gas type. T-linear variation of the critical field observed down to 0.03 K suggests the unusual situation that the entropy release across the transition remains finite [approximately 0.5 (J/K) x mol-Dy] as T-->0, in accordance with a breaking of the macroscopic degeneracy in the intermediate "kagomé ice" state.
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Affiliation(s)
- T Sakakibara
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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28
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Kamiyama T, Hiroi Z, Oikawa K. Crystal structure of superconducting pyrochlore oxide Cd 2Re 2O 7. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302093297] [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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29
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Vyaselev O, Arai K, Kobayashi K, Yamazaki J, Kodama K, Takigawa M, Hanawa M, Hiroi Z. Superconductivity and magnetic fluctuations in Cd(2))Re(2)O(7) via Cd nuclear magnetic resonance and re nuclear quadrupole resonance. Phys Rev Lett 2002; 89:017001. [PMID: 12097064 DOI: 10.1103/physrevlett.89.017001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2002] [Indexed: 05/23/2023]
Abstract
We report Cd nuclear magnetic resonance (NMR) and Re nuclear quadrupole resonance (NQR) studies on Cd(2)Re(2)O(7), the first superconductor among pyrochlore oxides (T(c) approximately 1 K). The Re NQR spectrum at zero magnetic field below 100 K rules out any magnetic or charge order. The spin-lattice relaxation rate below T(c) exhibits a pronounced coherence peak and follows the weak-coupling BCS theory with nearly isotropic energy gap. The results of Cd NMR point to a moderate ferromagnetic enhancement at high temperatures followed by a rapid decrease of the density of states below the structural transition temperature of 200 K.
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Affiliation(s)
- O Vyaselev
- Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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30
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31
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Hiroi Z, Horiuchi S. High-voltage high-resolution electron microscopy study of alkaline-earth copper oxides. Microsc Res Tech 1998; 40:251-64. [PMID: 9523759 DOI: 10.1002/(sici)1097-0029(19980215)40:4<251::aid-jemt2>3.0.co;2-v] [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] [Indexed: 11/08/2022]
Abstract
Two families of alkaline-earth copper oxides are studied by using high-voltage high-resolution electron microscopy. One is Sr(n-1) Cu(n)O(2n-1) (n = 2, 3), the so-called spin-ladder compounds, and the other is ACuO2 (A = Ca-Sr) crystallizing in the infinite-layer structure, which is a parent structure for all copper oxide superconductors. It is demonstrated in the former compounds that oxygen columns as well as metal columns are directly imaged in a "structure" image. Moreover, twin-related lattice defects, which can be the origin of free Cu2+ spins observed previously in magnetic measurements, have been detected in SrCu2O3. An interesting irradiation effect under a 1,000-kV electron beam has been observed in the infinite-layer compound: An unusual structural phase transformation to a NaCl-type lattice is induced, accompanied by the formation of nm-size twin domains.
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Affiliation(s)
- Z Hiroi
- Institute for Chemical Research, Kyoto University, Japan.
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32
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Chong I, Hiroi Z, Izumi M, Shimoyama J, Nakayama Y, Kishio K, Terashima T, Bando Y, Takano M. High Critical-Current Density in the Heavily Pb-Doped Bi2Sr2CaCu2O8+delta Superconductor: Generation of Efficient Pinning Centers. Science 1997; 276:770-3. [PMID: 9115196 DOI: 10.1126/science.276.5313.770] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Critical-current density (Jc) is a parameter of primary importance for potential applications of high-temperature copper oxide superconductors. It is limited principally by the breakdown of zero-resistive current due to thermally activated flux flow at high temperatures and high magnetic fields. One promising method to overcome this limitation is to introduce efficient pinning centers into crystals that can suppress the flux flow. A marked increase in Jc was observed in Bi2Sr2CaCu2O8+delta (Bi-2212) single crystals doped with a large amount of Pb. By electron microscopy, characteristic microstructures were revealed that probably underlie the observed enhancement in Jc: thin (10 to 50 nanometers), platelike domains having a modulation-free structure appeared with spacings of 50 to 100 nanometers along the b axis.
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Affiliation(s)
- I Chong
- I. Chong, Z. Hiroi, M. Izumi, T. Terashima, Y. Bando, M. Takano, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611, Japan. J. Shimoyama, Y. Nakayama, K. Kishio, Department of Applied Chemistry, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
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Hiroi Z, Amelinckx S, Kobayashi N. Microscopic origin of dimerization in the CuO2 chains in Sr14Cu24O41. Phys Rev B Condens Matter 1996; 54:15849-15855. [PMID: 9985653 DOI: 10.1103/physrevb.54.15849] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [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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Khasanova NR, Izumi F, Hiroi Z, Takano M, Huang Q, Santoro A. Redetermination of the Structure of La2Cu2O5 by Neutron Powder Diffraction. Acta Crystallogr C 1996. [DOI: 10.1107/s0108270196006646] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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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Kadono R, Okajima H, Yamashita A, Ishii K, Yokoo T, Akimitsu J, Kobayashi N, Hiroi Z, Takano M, Nagamine K. Long-range magnetic ordering in the spin ladder compound LaCuO2.5 probed by muon-spin relaxation. Phys Rev B Condens Matter 1996; 54:R9628-R9630. [PMID: 9984777 DOI: 10.1103/physrevb.54.r9628] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [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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Jorgensen JD, Chmaissem O, Argyriou DN, Hinks DG, Guptasarma P, Shimoyama J, Kishio K, Yamaura K, Hiroi Z, Takano M, Storey BG, Zhang H, Marks LD, Wang YY, Dravid VP, Dabrowski B. Structure modification to increase flux pinning in Hg–Ba–Ca–Cu–O superconductors. Acta Crystallogr A 1996. [DOI: 10.1107/s0108767396084310] [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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Chmaissem O, Jorgensen JD, Yamaura K, Hiroi Z, Takano M, Shimoyama J, Kishio K. Crystal structures of Hg-Sr-Ca-Cu-O superconductors with enhanced flux pinning: Hg1-xRexSr2Can-1CunO2n+2+ delta (n=2,3; x. Phys Rev B Condens Matter 1996; 53:14647-14655. [PMID: 9983266 DOI: 10.1103/physrevb.53.14647] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [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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Matsumoto S, Kitaoka Y, Ishida K, Asayama K, Hiroi Z, Kobayashi N, Takano M. Competition between the singlet-spin liquid state and the magnetic ground state in a two-chain spin-1/2 antiferromagnetic ladder compound LaCuO2.5: A 63Cu NMR study. Phys Rev B Condens Matter 1996; 53:R11942-R11945. [PMID: 9982893 DOI: 10.1103/physrevb.53.r11942] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [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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Ishida K, Kitaoka Y, Tokunaga Y, Matsumoto S, Asayama K, Azuma M, Hiroi Z, Takano M. Spin correlation and spin gap in quasi-one-dimensional spin-1/2 cuprate oxides: A 63Cu NMR study. Phys Rev B Condens Matter 1996; 53:2827-2834. [PMID: 9983796 DOI: 10.1103/physrevb.53.2827] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [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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Argyriou DN, Jorgensen JD, Hitterman RL, Hiroi Z, Kobayashi N, Takano M. Structure and superconductivity without apical oxygens in (Ca,Na)2CuO2Cl2. Phys Rev B Condens Matter 1995; 51:8434-8437. [PMID: 9977455 DOI: 10.1103/physrevb.51.8434] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
The crystal chemistry of the alkaline-earth cupric oxides stabilized at high pressure was studied by high-resolution electron microscopy. Two families of superconductors, (Ca1-ySry)1-xCuO2 and Srn+1CunO2n+1+delta (n = 1, 2), and one series of semiconductors, Srn-1Cun+1O2n, are reported. Their structural characteristics are systematically interpreted on the basis of the simple infinite-layer structure seen in SrCuO2. Microstructures and their relevance to high-Tc superconductivity are discussed, particularly in the alkaline-earth-deficient infinite-layer phase.
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Affiliation(s)
- Z Hiroi
- Institute for Chemical Research, Kyoto University, Japan
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Azuma M, Hiroi Z, Takano M, Ishida K, Kitaoka Y. Observation of a spin gap in SrCu2O3 comprising Ssin-12 quasi-1D two-leg ladders. Phys Rev Lett 1994; 73:3463-3466. [PMID: 10057387 DOI: 10.1103/physrevlett.73.3463] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.8] [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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Hiroi Z, Takano M, Bando Y, Sato A, Takeda Y. Superconducting properties of La2-xBixCuO4+ delta : Suppression of the phase separation observed for La2CuO4+ delta. Phys Rev B Condens Matter 1992; 46:14857-14860. [PMID: 10003586 DOI: 10.1103/physrevb.46.14857] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Hiroi Z, Azuma M, Takano M, Bando Y. A new homologous series Srn−1Cun+1O2n found in the SrOCuO system treated under high pressure. J SOLID STATE CHEM 1991. [DOI: 10.1016/0022-4596(91)90394-w] [Citation(s) in RCA: 278] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hiroi Z, Obata T, Takano M, Bando Y, Takeda Y, Yamamoto O. Ordering of interstitial oxygen atoms in La2NiO4+ delta observed by transmission electron microscopy. Phys Rev B Condens Matter 1990; 41:11665-11668. [PMID: 9993607 DOI: 10.1103/physrevb.41.11665] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [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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