1
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Kobayashi H, Sakaguchi Y, Kitagawa H, Oura M, Ikeda S, Kuga K, Suzuki S, Nakatsuji S, Masuda R, Kobayashi Y, Seto M, Yoda Y, Tamasaku K, Komijani Y, Chandra P, Coleman P. Observation of a critical charge mode in a strange metal. Science 2023. [PMID: 36862771 DOI: 10.1126/science.abc4787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Understanding the strange metallic behavior that develops at the brink of localization in quantum materials requires probing the underlying electronic charge dynamics. Using synchrotron radiation-based Mössbauer spectroscopy, we studied the charge fluctuations of the strange metal phase of β-YbAlB4 as a function of temperature and pressure. We found that the usual single absorption peak in the Fermi-liquid regime splits into two peaks upon entering the critical regime. We interpret this spectrum as a single nuclear transition, modulated by nearby electronic valence fluctuations whose long time scales are further enhanced by the formation of charged polarons. These critical charge fluctuations may prove to be a distinct signature of strange metals.
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Affiliation(s)
- Hisao Kobayashi
- Graduate School of Material Science, University of Hyogo, 3-2-1 Koto, Hyogo 678-1297, Japan.,RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Yui Sakaguchi
- Graduate School of Material Science, University of Hyogo, 3-2-1 Koto, Hyogo 678-1297, Japan
| | - Hayato Kitagawa
- Graduate School of Material Science, University of Hyogo, 3-2-1 Koto, Hyogo 678-1297, Japan.,RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Momoko Oura
- Graduate School of Material Science, University of Hyogo, 3-2-1 Koto, Hyogo 678-1297, Japan.,RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Shugo Ikeda
- Graduate School of Material Science, University of Hyogo, 3-2-1 Koto, Hyogo 678-1297, Japan.,RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Kentaro Kuga
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Shintaro Suzuki
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Satoru Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan.,Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.,Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Ryo Masuda
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan.,Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan.,Graduate School of Science and Technology, Hirosaki University, Aomori 036-8561 Japan
| | - Yasuhiro Kobayashi
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan.,Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
| | - Makoto Seto
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan.,Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
| | - Yoshitaka Yoda
- Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan
| | | | - Yashar Komijani
- Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011, USA.,Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - Premala Chandra
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - Piers Coleman
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA.,Hubbard Theory Consortium, Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
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Strongly Correlated Quantum Spin Liquids versus Heavy Fermion Metals: A Review. MATERIALS 2022; 15:ma15113901. [PMID: 35683199 PMCID: PMC9182384 DOI: 10.3390/ma15113901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/15/2022] [Accepted: 05/25/2022] [Indexed: 12/04/2022]
Abstract
This review considers the topological fermion condensation quantum phase transition (FCQPT) that explains the complex behavior of strongly correlated Fermi systems, such as frustrated insulators with quantum spin liquid and heavy fermion metals. The review contrasts theoretical consideration with recent experimental data collected on both heavy fermion metals (HF) and frustrated insulators. Such a method allows to understand experimental data. We also consider experimental data collected on quantum spin liquid in Lu3Cu2Sb3O14 and quasi-one dimensional (1D) quantum spin liquid in both YbAlO3 and Cu(C4H4N2)(NO3)2 with the aim to establish a sound theoretical explanation for the observed scaling laws, Landau Fermi liquid (LFL) and non-Fermi-liquid (NFL) behavior exhibited by these frustrated insulators. The recent experimental data on the heavy-fermion metal α−YbAl1−xFexB4, with x=0.014, and on its sister compounds β−YbAlB4 and YbCo2Ge4, carried out under the application of magnetic field as a control parameter are analyzed. We show that the thermodynamic and transport properties as well as the empirical scaling laws follow from the fermion condensation theory. We explain how both the similarity and the difference in the thermodynamic and transport properties of α−YbAl1−xFexB4 and in its sister compounds β−YbAlB4 and YbCo2Ge4 emerge, as well as establish connection of these (HF) metals with insulators Lu3Cu2Sb3O14, Cu(C4H4N2)(NO3)2 and YbAlO3. We demonstrate that the universal LFL and NFL behavior emerge because the HF compounds and the frustrated insulators are located near the topological FCQPT or are driven by the application of magnetic fields.
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3
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Anisotropy-driven quantum criticality in an intermediate valence system. Nat Commun 2022; 13:2141. [PMID: 35440657 PMCID: PMC9019086 DOI: 10.1038/s41467-022-29757-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 03/29/2022] [Indexed: 11/08/2022] Open
Abstract
Intermetallic compounds containing f-electron elements have been prototypical materials for investigating strong electron correlations and quantum criticality (QC). Their heavy fermion ground state evoked by the magnetic f-electrons is susceptible to the onset of quantum phases, such as magnetism or superconductivity, due to the enhanced effective mass (m*) and a corresponding decrease of the Fermi temperature. However, the presence of f-electron valence fluctuations to a non-magnetic state is regarded an anathema to QC, as it usually generates a paramagnetic Fermi-liquid state with quasiparticles of moderate m*. Such systems are typically isotropic, with a characteristic energy scale T0 of the order of hundreds of kelvins that require large magnetic fields or pressures to promote a valence or magnetic instability. Here we show the discovery of a quantum critical behaviour and a Lifshitz transition under low magnetic field in an intermediate valence compound α-YbAlB4. The QC origin is attributed to the anisotropic hybridization between the conduction and localized f-electrons. These findings suggest a new route to bypass the large valence energy scale in developing the QC. The nature of quantum criticality in intermetallic f-electron compounds exhibiting valence fluctuations is not well understood. Here, using a combination of experimental techniques, the authors attribute quantum criticality in YbAlB4 to the anisotropic hybridization between the conduction and f-electrons.
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4
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Kuga K, Kanai Y, Fujiwara H, Yamagami K, Hamamoto S, Aoyama Y, Sekiyama A, Higashiya A, Kadono T, Imada S, Yamasaki A, Tanaka A, Tamasaku K, Yabashi M, Ishikawa T, Nakatsuji S, Kiss T. Effect of Anisotropic Hybridization in YbAlB_{4} Probed by Linear Dichroism in Core-Level Hard X-Ray Photoemission Spectroscopy. PHYSICAL REVIEW LETTERS 2019; 123:036404. [PMID: 31386467 DOI: 10.1103/physrevlett.123.036404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Indexed: 06/10/2023]
Abstract
We have probed the crystalline electric-field ground states of pure |J=7/2,J_{z}=±5/2⟩ as well as the anisotropic c-f hybridization in both valence fluctuating systems α- and β-YbAlB_{4} by linear polarization dependence of angle-resolved core level photoemission spectroscopy. Interestingly, the small but distinct difference between α- and β-YbAlB_{4} was found in the polar angle dependence of linear dichroism, indicating the difference in the anisotropy of c-f hybridization, which may be a key to understanding a heavy Fermi liquid state in α-YbAlB_{4} and a quantum critical state in β-YbAlB_{4}.
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Affiliation(s)
- Kentaro Kuga
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - Yuina Kanai
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hidenori Fujiwara
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kohei Yamagami
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Satoru Hamamoto
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yuichi Aoyama
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Akira Sekiyama
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Atsushi Higashiya
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Faculty of Science and Engineering, Setsunan University, Neyagawa, Osaka 572-8508, Japan
| | - Toshiharu Kadono
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- College of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Shin Imada
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- College of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Atsushi Yamasaki
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Faculty of Science and Engineering, Konan University, Kobe, Hyogo 658-8501, Japan
| | - Arata Tanaka
- Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | | | | | | | - Satoru Nakatsuji
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Takayuki Kiss
- RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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5
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Komijani Y, Coleman P. Model for a Ferromagnetic Quantum Critical Point in a 1D Kondo Lattice. PHYSICAL REVIEW LETTERS 2018; 120:157206. [PMID: 29756902 DOI: 10.1103/physrevlett.120.157206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Indexed: 06/08/2023]
Abstract
Motivated by recent experiments, we study a quasi-one-dimensional model of a Kondo lattice with ferromagnetic coupling between the spins. Using bosonization and dynamical large-N techniques, we establish the presence of a Fermi liquid and a magnetic phase separated by a local quantum critical point, governed by the Kondo breakdown picture. Thermodynamic properties are studied and a gapless charged mode at the quantum critical point is highlighted.
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Affiliation(s)
- Yashar Komijani
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Piers Coleman
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom
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6
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Ryu H, Abeykoon M, Bozin E, Matsumoto Y, Nakatsuji S, Petrovic C. Multiband electronic transport in α-Yb1-x Sr x AlB4 [x = 0, 0.19(3)] single crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:425602. [PMID: 27541840 DOI: 10.1088/0953-8984/28/42/425602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report on the evidence for the multiband electronic transport in α-YbAlB4 and α-Yb0.81(2)Sr0.19(3)AlB4. Multiband transport reveals itself below 10 K in both compounds via Hall effect measurements, whereas anisotropic magnetic ground state sets in below 3 K in α-Yb0.81(2)Sr0.19(3)AlB4. Our results show that Sr(2+) substitution enhances conductivity, but does not change the quasiparticle mass of bands induced by heavy fermion hybridization.
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Affiliation(s)
- Hyejin Ryu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA
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7
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Tomita T, Kuga K, Uwatoko Y, Coleman P, Nakatsuji S. Strange metal without magnetic criticality. Science 2015; 349:506-9. [DOI: 10.1126/science.1262054] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 07/06/2015] [Indexed: 11/02/2022]
Affiliation(s)
- Takahiro Tomita
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- College of Humanities and Sciences, Nihon University, Setagaya 156-8550, Japan
| | - Kentaro Kuga
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Yoshiya Uwatoko
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Piers Coleman
- Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, Piscataway, N.J. 08854, USA
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| | - Satoru Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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8
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Khuntia P, Peratheepan P, Strydom AM, Utsumi Y, Ko KT, Tsuei KD, Tjeng LH, Steglich F, Baenitz M. Contiguous 3d and 4f magnetism: strongly correlated 3d electrons in YbFe2Al10. PHYSICAL REVIEW LETTERS 2014; 113:216403. [PMID: 25479509 DOI: 10.1103/physrevlett.113.216403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Indexed: 06/04/2023]
Abstract
We present magnetization, specific heat, and (27)Al NMR investigations on YbFe2Al10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln(T0/T) divergence of the low-T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard-x-ray photoemission spectroscopy study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, Yb(3+) carries a full and stable moment, and Fe carries a moment of about 3.1 μB. The enhanced value of the Sommerfeld-Wilson ratio and the dynamic scaling of the spin-lattice relaxation rate divided by T[(27)(1/T1T)] with static susceptibility suggests admixed ferromagnetic correlations. (27)(1/T1T) simultaneously tracks the valence fluctuations from the 4f Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe 3d moments at low temperature; the latter evolve out of an Yb 4f admixed conduction band.
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Affiliation(s)
- P Khuntia
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - P Peratheepan
- Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa and Department of Physics, Eastern University, Vantharumoolai, Chenkalady 30350, Sri Lanka
| | - A M Strydom
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany and Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa
| | - Y Utsumi
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - K-T Ko
- Max Planck POSTECH Center for Complex Phase Materials, 01187 Dresden, Germany and Pohang 790-784, Korea
| | - K-D Tsuei
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu 30077, Taiwan
| | - L H Tjeng
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - F Steglich
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - M Baenitz
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
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9
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Ramires A, Coleman P. Theory of the electron spin resonance in the heavy fermion metal β-YbAlB4. PHYSICAL REVIEW LETTERS 2014; 112:116405. [PMID: 24702395 DOI: 10.1103/physrevlett.112.116405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Indexed: 06/03/2023]
Abstract
The heavy fermion metal β-YbAlB4 exhibits a bulk room temperature conduction electron spin resonance (ESR) signal which evolves into an Ising-anisotropic f-electron signal exhibiting hyperfine features at low temperatures. We develop a theory for this phenomenon based on the development of resonant scattering off a periodic array of Kondo centers. We show that the hyperfine structure arises from the scattering off the Yb atoms with nonzero nuclear spin, while the constancy of the ESR intensity is a consequence of the presence of crystal electric field excitations of the order of the hybridization strength.
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Affiliation(s)
- Aline Ramires
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Piers Coleman
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
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10
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Ramires A, Coleman P, Nevidomskyy AH, Tsvelik AM. β-YbAlB4: a critical nodal metal. PHYSICAL REVIEW LETTERS 2012; 109:176404. [PMID: 23215209 DOI: 10.1103/physrevlett.109.176404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Indexed: 06/01/2023]
Abstract
We propose a model for the intrinsic quantum criticality of β-YbAlB(4), in which a vortex in momentum space gives rise to a new type of Fermi surface singularity. The unquenched angular momentum of the |J=7/2,m(J)=±5/2> Yb 4f states generates a momentum-space line defect in the hybridization between 4f and conduction electrons, leading to a quasi-two-dimensional Fermi surface with a k(⊥)(4) dispersion and a singular density of states proportional to E(-1/2). We discuss the implications of this line node in momentum space for our current understanding of quantum criticality and its interplay with topology.
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Affiliation(s)
- Aline Ramires
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
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11
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O'Farrell ECT, Matsumoto Y, Nakatsuji S. Evolution of c-f hybridization and two-component Hall effect in β-YbAlB4. PHYSICAL REVIEW LETTERS 2012; 109:176405. [PMID: 23215210 DOI: 10.1103/physrevlett.109.176405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Indexed: 06/01/2023]
Abstract
β-YbAlB(4) is the unique heavy fermion superconductor that exhibits unconventional quantum criticality without tuning in a strongly intermediate valence state. Despite the large coherence temperature, set by the peak of the longitudinal resistivity, our Hall effect measurements reveal that resonant skew scattering from incoherent local moments persists down to at least ~40 K, where the Hall coefficient exhibits a distinct minimum signaling another formation of coherence. The observation strongly suggests that the hybridization between f moments and conduction electrons has a two-component character with distinct Kondo or coherence scales T(K) of ~40 K and 200 K; this is confirmed by the magnetic field dependence of ρ(xy).
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Affiliation(s)
- E C T O'Farrell
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan 277-8581.
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12
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Morosan E, Natelson D, Nevidomskyy AH, Si Q. Strongly correlated materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:4896-4923. [PMID: 22893361 DOI: 10.1002/adma.201202018] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Indexed: 06/01/2023]
Abstract
Strongly correlated materials are profoundly affected by the repulsive electron-electron interaction. This stands in contrast to many commonly used materials such as silicon and aluminum, whose properties are comparatively unaffected by the Coulomb repulsion. Correlated materials often have remarkable properties and transitions between distinct, competing phases with dramatically different electronic and magnetic orders. These rich phenomena are fascinating from the basic science perspective and offer possibilities for technological applications. This article looks at these materials through the lens of research performed at Rice University. Topics examined include: Quantum phase transitions and quantum criticality in "heavy fermion" materials and the iron pnictide high temperature superconductors; computational ab initio methods to examine strongly correlated materials and their interface with analytical theory techniques; layered dichalcogenides as example correlated materials with rich phases (charge density waves, superconductivity, hard ferromagnetism) that may be tuned by composition, pressure, and magnetic field; and nanostructure methods applied to the correlated oxides VO₂ and Fe₃O₄, where metal-insulator transitions can be manipulated by doping at the nanoscale or driving the system out of equilibrium. We conclude with a discussion of the exciting prospects for this class of materials.
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Affiliation(s)
- Emilia Morosan
- Department of Physics and Astronomy MS 61, Rice University, 6100 Main St., Houston, TX 77005, USA
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13
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Willers T, Strigari F, Hiraoka N, Cai YQ, Haverkort MW, Tsuei KD, Liao YF, Seiro S, Geibel C, Steglich F, Tjeng LH, Severing A. Determining the in-plane orientation of the ground-state orbital of CeCu2Si2. PHYSICAL REVIEW LETTERS 2012; 109:046401. [PMID: 23006099 DOI: 10.1103/physrevlett.109.046401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Indexed: 06/01/2023]
Abstract
We have successfully determined the hitherto unknown sign of the B(4)(4) Stevens crystal-field parameter of the tetragonal heavy-fermion compound CeCu(2)Si(2) using vector q-dependent nonresonant inelastic x-ray scattering experiments at the cerium N(4,5) edge. The observed difference between the two different directions, q∥[100] and q∥[110], is due to the anisotropy of the crystal-field ground state in the (001) plane and is observable only because of the utilization of higher than dipole transitions possible in nonresonant inelastic x-ray scattering. This approach allows us to go beyond the specific limitations of dc magnetic susceptibility, inelastic neutron scattering, and soft x-ray spectroscopy, and provides us with a reliable information about the orbital state of the 4f electrons relevant for the quantitative modeling of the quasiparticles and their interactions in heavy-fermion systems.
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Affiliation(s)
- T Willers
- Institute of Physics II, University of Cologne, Zülpicher Straße 77, D-50937 Cologne, Germany
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14
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Holanda LM, Vargas JM, Iwamoto W, Rettori C, Nakatsuji S, Kuga K, Fisk Z, Oseroff SB, Pagliuso PG. Quantum critical Kondo quasiparticles probed by ESR in β-YbAlB₄. PHYSICAL REVIEW LETTERS 2011; 107:026402. [PMID: 21797626 DOI: 10.1103/physrevlett.107.026402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Indexed: 05/31/2023]
Abstract
Electron spin resonance (ESR) can probe conduction electrons (CE) and local moment (LM) spin systems in different materials. A CE spin resonance (CESR) is observed in metallic systems based on light elements or with enhanced Pauli susceptibility. LM ESR can be seen in compounds with paramagnetic ions and localized d or f electrons. Here we report a remarkable and unprecedented ESR signal in the heavy-fermion superconductor β-YbAlB₄ [S. Nakatsuji et al., Nature Phys. 4, 603 (2008)] which behaves as a CESR at high temperatures and acquires characteristics of the Yb³⁺ LM ESR at low temperature. This dual behavior strikes as an in situ unique observation of the Kondo quasiparticles in a quantum critical regime. The proximity to a quantum critical point may favor the appearance of this dual character of the ESR signal in β-YbAlB₄.
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Affiliation(s)
- L M Holanda
- Instituto de Física Gleb Wataghin, UNICAMP, Campinas-SP, 13083-970, Brazil
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15
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Irkhin VY. The Kondo-lattice state and non-Fermi-liquid behavior in the presence of Van Hove singularities. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:065602. [PMID: 21406931 DOI: 10.1088/0953-8984/23/6/065602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A scaling consideration of the Kondo lattices is performed with account of logarithmic Van Hove singularities (VHS) in the electron density of states. The scaling trajectories are presented for different magnetic phases. It is demonstrated that VHS lead to a considerable increase of the non-Fermi-liquid behavior region owing to softening of magnon branches during the renormalization process. Although the effective coupling constant remains moderate, the renormalized magnetic moment and spin-fluctuation frequency can decrease by several orders of magnitude. A possible application to f-systems and weak itinerant magnets is discussed.
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Affiliation(s)
- V Yu Irkhin
- Institute of Metal Physics, 620041 Ekaterinburg, Russia.
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16
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Matsumoto Y, Nakatsuji S, Kuga K, Karaki Y, Horie N, Shimura Y, Sakakibara T, Nevidomskyy AH, Coleman P. Quantum Criticality Without Tuning in the Mixed Valence Compound β-YbAlB
4. Science 2011; 331:316-9. [PMID: 21252341 DOI: 10.1126/science.1197531] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Yosuke Matsumoto
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Satoru Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Kentaro Kuga
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Yoshitomo Karaki
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Naoki Horie
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Yasuyuki Shimura
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Toshiro Sakakibara
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Andriy H. Nevidomskyy
- Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - Piers Coleman
- Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
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17
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Okawa M, Matsunami M, Ishizaka K, Eguchi R, Taguchi M, Chainani A, Takata Y, Yabashi M, Tamasaku K, Nishino Y, Ishikawa T, Kuga K, Horie N, Nakatsuji S, Shin S. Strong valence fluctuation in the quantum critical heavy fermion superconductor β-YbAlB4: a hard x-ray photoemission study. PHYSICAL REVIEW LETTERS 2010; 104:247201. [PMID: 20867330 DOI: 10.1103/physrevlett.104.247201] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Indexed: 05/29/2023]
Abstract
Electronic structures of the quantum critical superconductor β-YbAlB4 and its polymorph α-YbAlB4 are investigated by using bulk-sensitive hard x-ray photoemission spectroscopy. From the Yb 3d core level spectra, the values of the Yb valence are estimated to be ∼2.73 and ∼2.75 for α- and β-YbAlB4, respectively, thus providing clear evidence for valence fluctuations. The valence band spectra of these compounds also show Yb2+ peaks at the Fermi level. These observations establish an unambiguous case of a strong mixed valence at quantum criticality for the first time among heavy fermion systems, calling for a novel scheme for a quantum critical model beyond the conventional Doniach picture in β-YbAlB4.
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Affiliation(s)
- M Okawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
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18
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Custers J, Gegenwart P, Geibel C, Steglich F, Coleman P, Paschen S. Evidence for a non-Fermi-liquid phase in Ge-substituted YbRh2Si2. PHYSICAL REVIEW LETTERS 2010; 104:186402. [PMID: 20482193 DOI: 10.1103/physrevlett.104.186402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 01/27/2010] [Indexed: 05/29/2023]
Abstract
The canonical view of heavy fermion quantum criticality assumes a single quantum critical point separating the paramagnet from the antiferromagnet. However, recent experiments on Yb-based heavy fermion compounds suggest the presence of non-Fermi liquid behavior over a finite zero-temperature region. Using detailed susceptibility and transport measurements we show that the classic quantum critical system, Ge-substituted YbRh(2)Si(2), also displays such behavior. We advance arguments that this is not due to a disorder-smeared quantum critical point, but represents a new class of metallic phase.
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Affiliation(s)
- J Custers
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
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19
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O'Farrell ECT, Tompsett DA, Sebastian SE, Harrison N, Capan C, Balicas L, Kuga K, Matsuo A, Kindo K, Tokunaga M, Nakatsuji S, Csányi G, Fisk Z, Sutherland ML. Role of f electrons in the Fermi surface of the heavy fermion superconductor beta-YbAlB4. PHYSICAL REVIEW LETTERS 2009; 102:216402. [PMID: 19519118 DOI: 10.1103/physrevlett.102.216402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Indexed: 05/27/2023]
Abstract
We present a detailed quantum oscillation study of the Fermi surface of the recently discovered Yb-based heavy fermion superconductor beta-YbAlB4. We compare the data, obtained at fields from 10 to 45 T, to band structure calculations performed using the local density approximation. Analysis of the data suggests that f holes participate in the Fermi surface up to the highest magnetic fields studied. We comment on the significance of these findings for the unconventional superconducting properties of this material.
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Affiliation(s)
- E C T O'Farrell
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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