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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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Cai A, Yu Z, Hu H, Kirchner S, Si Q. Dynamical Scaling of Charge and Spin Responses at a Kondo Destruction Quantum Critical Point. PHYSICAL REVIEW LETTERS 2020; 124:027205. [PMID: 32004044 DOI: 10.1103/physrevlett.124.027205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Indexed: 06/10/2023]
Abstract
Quantum critical points often arise in metals perched at the border of an antiferromagnetic order. The recent observation of singular and dynamically scaling charge conductivity in an antiferromagnetic quantum critical heavy fermion metal implicates beyond-Landau quantum criticality. Here we study the charge and spin dynamics of a Kondo destruction quantum critical point (QCP), as realized in an SU(2)-symmetric Bose-Fermi Kondo model. We find that the critical exponents and scaling functions of the spin and single-particle responses of the QCP in the SU(2) case are essentially the same as those of the large-N limit, showing that 1/N corrections are subleading. Building on this insight, we demonstrate that the charge responses at the Kondo destruction QCP are singular and obey ω/T scaling. This property persists at the Kondo destruction QCP of the SU(2)-symmetric Kondo lattice model.
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Affiliation(s)
- Ang Cai
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Zuodong Yu
- Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Province Key Laboratory of Quantum Technology and Devices, Zhejiang University, Hangzhou 310027, China
| | - Haoyu Hu
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Stefan Kirchner
- Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Zhejiang Province Key Laboratory of Quantum Technology and Devices, Zhejiang University, Hangzhou 310027, China
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
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Komijani Y, Coleman P. Emergent Critical Charge Fluctuations at the Kondo Breakdown of Heavy Fermions. PHYSICAL REVIEW LETTERS 2019; 122:217001. [PMID: 31283303 DOI: 10.1103/physrevlett.122.217001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Indexed: 06/09/2023]
Abstract
One of the challenges in strongly correlated electron systems is to understand the anomalous electronic behavior that develops at an antiferromagnetic quantum critical point (QCP), a phenomenon that has been extensively studied in heavy-fermion materials. Current theories have focused on the critical spin fluctuations and associated breakdown of the Kondo effect. Here we argue that the abrupt change in the Fermi surface volume that accompanies heavy-fermion criticality leads to critical charge fluctuations. Using a model one-dimensional Kondo lattice, in which each moment is connected to a separate conduction bath, we show that a Kondo breakdown transition develops between a heavy Fermi liquid and a gapped spin liquid via a QCP with ω/T scaling, which features a critical charge mode directly associated with the breakup of Kondo singlets. We discuss the possible implications of this emergent charge mode for experiments.
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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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Wagner C, Chowdhury T, Pixley JH, Ingersent K. Long-Range Entanglement near a Kondo-Destruction Quantum Critical Point. PHYSICAL REVIEW LETTERS 2018; 121:147602. [PMID: 30339433 DOI: 10.1103/physrevlett.121.147602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/18/2018] [Indexed: 06/08/2023]
Abstract
The numerical renormalization group is used to study quantum entanglement in the Kondo impurity model with a density of states ρ(ϵ)∝|ϵ|^{r} (0<r<1/2) that vanishes at the Fermi energy ϵ=0. This nonintegrable model features a Kondo-destruction quantum critical point (QCP) separating a partially screened phase from a local-moment phase. The impurity contribution S_{e}^{imp} to the entanglement entropy between a region of radius R around the magnetic impurity and the rest of the system reveals a length scale R^{*} that distinguishes a region R≪R^{*} of strong critical entanglement from one R≫R^{*} of weak entanglement. Within each phase, S_{e}^{imp} is a universal function of R/R^{*} with a power-law decay for R/R^{*}≫1. The entanglement length R^{*} diverges on approach to the interacting QCP, showing that the critical Kondo screening cloud subsumes the entire system as the impurity becomes maximally entangled with the conduction band. This work has implications for entanglement calculations in other models and for the nature of heavy-fermion quantum criticality.
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Affiliation(s)
- Christopher Wagner
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - Tathagata Chowdhury
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77a, 50937 Köln, Germany
| | - J H Pixley
- Department of Physics and Astronomy, Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854 USA
- Condensed Matter Theory Center and the Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Kevin Ingersent
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
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Kuga K, Matsumoto Y, Okawa M, Suzuki S, Tomita T, Sone K, Shimura Y, Sakakibara T, Nishio-Hamane D, Karaki Y, Takata Y, Matsunami M, Eguchi R, Taguchi M, Chainani A, Shin S, Tamasaku K, Nishino Y, Yabashi M, Ishikawa T, Nakatsuji S. Quantum valence criticality in a correlated metal. SCIENCE ADVANCES 2018; 4:eaao3547. [PMID: 29492456 PMCID: PMC5825215 DOI: 10.1126/sciadv.aao3547] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 01/19/2018] [Indexed: 06/08/2023]
Abstract
A valence critical end point existing near the absolute zero provides a unique case for the study of a quantum version of the strong density fluctuation at the Widom line in the supercritical fluids. Although singular charge and orbital dynamics are suggested theoretically to alter the electronic structure significantly, breaking down the standard quasi-particle picture, this has never been confirmed experimentally to date. We provide the first empirical evidence that the proximity to quantum valence criticality leads to a clear breakdown of Fermi liquid behavior. Our detailed study of the mixed valence compound α-YbAlB4 reveals that a small chemical substitution induces a sharp valence crossover, accompanied by a pronounced non-Fermi liquid behavior characterized by a divergent effective mass and unusual T/B scaling in the magnetization.
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Affiliation(s)
- Kentaro Kuga
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
| | - Yosuke Matsumoto
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Mario Okawa
- 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
| | - Takahiro Tomita
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Keita Sone
- 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
| | | | - Yoshitomo Karaki
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- Faculty of Education, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan
| | | | - Masaharu Matsunami
- Ultraviolet Synchrotron Orbital Radiation Facility, Institute for Molecular Science and The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Ritsuko Eguchi
- Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan
| | | | - Ashish Chainani
- RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Shik Shin
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
| | | | - Yoshinori Nishino
- RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan
| | | | | | - Satoru Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- Core Research for Evolutionary Science and Technology, Japan Science and Technology Agency, Chiyoda, Tokyo 102-0076, Japan
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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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Fritz L, Vojta M. The physics of Kondo impurities in graphene. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:032501. [PMID: 23411583 DOI: 10.1088/0034-4885/76/3/032501] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This article summarizes our understanding of the Kondo effect in graphene, primarily from a theoretical perspective. We shall describe different ways to create magnetic moments in graphene, either by adatom deposition or via defects. For dilute moments, the theoretical description is in terms of effective Anderson or Kondo impurity models coupled to graphene's Dirac electrons. We shall discuss in detail the physics of these models, including their quantum phase transitions and the effect of carrier doping, and confront this with existing experimental data. Finally, we will point out connections to other quantum impurity problems, e.g., in unconventional superconductors, topological insulators, and quantum spin liquids.
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Affiliation(s)
- Lars Fritz
- Institut für Theoretische Physik, Universität zu Köln, 50937 Köln, Germany.
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