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Wang J, Yang YF. Nonlocal Kondo effect and two-fluid picture revealed in an exactly solvable model. PNAS NEXUS 2023; 2:pgad169. [PMID: 37275258 PMCID: PMC10235911 DOI: 10.1093/pnasnexus/pgad169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023]
Abstract
Understanding the nature of local-itinerant transition of strongly correlated electrons is one of the central problems in condensed matter physics. Heavy fermion systems describe the f-electron delocalization through Kondo interactions with conduction electrons. Tremendous efforts have been devoted to the so-called Kondo-destruction scenario, which predicts a dramatic local-to-itinerant quantum phase transition of f-electrons at zero temperature. On the other hand, two-fluid behaviors have been observed in many materials, suggesting coexistence of local and itinerant f-electrons over a broad temperature range but lacking a microscopic theoretical description. To elucidate this fundamental issue, here we propose an exactly solvable Kondo-Heisenberg model in which the spins are defined in the momentum space and the k-space Kondo interaction corresponds to a highly nonlocal spin scattering in the coordinate space. Its solution reveals a continuous evolution of the Fermi surfaces with Kondo interaction and two-fluid behaviors similar to those observed in real materials. The electron density violates the usual Luttinger's theorem, but follows a generalized one allowing for partially enlarged Fermi surfaces due to partial Kondo screening in the momentum space. Our results highlight the consequence of nonlocal Kondo interaction relevant for strong quantum fluctuation regions and provide important insight into the microscopic description of two-fluid phenomenology in heavy fermion systems.
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Affiliation(s)
- Jiangfan Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, Beijing 100190, China
- School of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China
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2
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Chatterjee S, Ruf JP, Wei HI, Finkelstein KD, Schlom DG, Shen KM. Lifshitz transition from valence fluctuations in YbAl 3. Nat Commun 2017; 8:852. [PMID: 29021552 PMCID: PMC5636910 DOI: 10.1038/s41467-017-00946-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 08/08/2017] [Indexed: 11/24/2022] Open
Abstract
In mixed-valent Kondo lattice systems, such as YbAl3, interactions between localized and delocalized electrons can lead to fluctuations between two different valence configurations with changing temperature or pressure. The impact of this change on the momentum-space electronic structure is essential for understanding their emergent properties, but has remained enigmatic. Here, by employing a combination of molecular beam epitaxy and in situ angle-resolved photoemission spectroscopy we show that valence fluctuations can lead to dramatic changes in the Fermi surface topology, even resulting in a Lifshitz transition. As the temperature is lowered, a small electron pocket in YbAl3 becomes completely unoccupied while the low-energy ytterbium (Yb) 4f states become increasingly itinerant, acquiring additional spectral weight, longer lifetimes, and well-defined dispersions. Our work presents a unified picture of how local valence fluctuations connect to momentum-space concepts such as band filling and Fermi surface topology in mixed valence systems. How the electronic structure of a mixed-valence system changes with respect to local chemical environment remains elusive. Here, Chatterjee et al. show that valence fluctuations of YbAl3 can lead to dramatic changes in the Fermi surface topology in reciprocal space.
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Affiliation(s)
- Shouvik Chatterjee
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY, 14853, USA.,Department of Electrical & Computer Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Jacob P Ruf
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Haofei I Wei
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Kenneth D Finkelstein
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
| | - Darrell G Schlom
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, 14853, USA
| | - Kyle M Shen
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY, 14853, USA. .,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, 14853, USA.
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3
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Xie N, Hu D, Yang YF. Hybridization oscillation in the one-dimensional Kondo-Heisenberg model with Kondo holes. Sci Rep 2017; 7:11924. [PMID: 28931941 PMCID: PMC5607262 DOI: 10.1038/s41598-017-12240-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/06/2017] [Indexed: 11/23/2022] Open
Abstract
We use the density matrix renormalization group method to study the properties of the one-dimensional Kondo-Heisenberg model doped with Kondo holes. We find that the perturbation of the Kondo holes to the local hybridization exhibits spatial oscillation pattern and its amplitude decays exponentially with distance away from the Kondo hole sites. The hybridization oscillation is correlated with both the charge density oscillation of the conduction electrons and the oscillation in the correlation function of the Heisenberg spins. In particular, we find that the oscillation wavelength for intermediate Kondo couplings is given by the Fermi wavevector of the large Fermi surface even before it is formed. This suggests that heavy electrons responsible for the oscillation are already present in this regime and start to accumulate around the to-be-formed large Fermi surface in the Brillouin zone.
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Affiliation(s)
- Neng Xie
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Danqing Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Yi-Feng Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China.
- Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China.
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4
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Abstract
We propose a phenomenological framework for three classes of Kondo lattice materials that incorporates the interplay between the fluctuations associated with the antiferromagnetic quantum critical point and those produced by the hybridization quantum critical point that marks the end of local moment behavior. We show that these fluctuations give rise to two distinct regions of quantum critical scaling: Hybridization fluctuations are responsible for the logarithmic scaling in the density of states of the heavy electron Kondo liquid that emerges below the coherence temperature [Formula: see text], whereas the unconventional power law scaling in the resistivity that emerges at lower temperatures below [Formula: see text] may reflect the combined effects of hybridization and antiferromagnetic quantum critical fluctuations. Our framework is supported by experimental measurements on CeCoIn5, CeRhIn5, and other heavy electron materials.
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Lonzarich G, Pines D, Yang YF. Toward a new microscopic framework for Kondo lattice materials. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:024501. [PMID: 27991444 DOI: 10.1088/1361-6633/80/2/024501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Understanding the emergence and subsequent behavior of heavy electrons in Kondo lattice materials is one of the grand challenges in condensed matter physics. From this perspective we review the progress that has been made during the past decade and suggest some directions for future research. Our focus will be on developing a new microscopic framework that incorporates the basic concepts that emerge from a phenomenological description of the key experimental findings.
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Affiliation(s)
- Gilbert Lonzarich
- Cavendish Laboratory, Department of Physics, Cambridge University, Cambridge CB3 0HE, UK
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Xiang ZJ, Wang NZ, Wang AF, Zhao D, Sun ZL, Luo XG, Wu T, Chen XH. Incoherence-coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A = K, Rb, Cs): evidence from electrical transport properties. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:425702. [PMID: 27589485 DOI: 10.1088/0953-8984/28/42/425702] [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 study the normal-state transport properties of AFe2As2 (A = K, Rb and Cs) single crystals using Hall coefficient, resistivity and magnetoresistance (MR) measurements. In all three materials, the Hall coefficient R H shows a strong temperature dependence, which is typical for multi-band systems. In particular, R H develops an upturn below a characteristic temperature [Formula: see text], which is in agreement with the incoherence-coherence crossover reported in recent nuclear magnetic resonance studies. A Fermi-liquid-like state, characterized by T (2) behavior of the resistivity and a positive orbital MR obeying Kohler's rule, emerges below T FL ∼0.4 [Formula: see text]. The superconducting transition temperature T c experiences a simultaneous suppression with [Formula: see text] and T FL as the alkali ion's radius increases from A = K to A = Cs, suggesting that the unconventional superconductivity in the AFe2As2 series is related to the strength of the electronic coherence. A phase diagram, similar to that in the heavy fermion Kondo lattice system, is obtained. Based on all the experimental evidence, we argue that the physical properties of this family of heavily hole-doped Fe-based superconductors are controlled by the hybridization between itinerant carriers and localized orbitals, and the Kondo scenario could be effective in such a case.
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Affiliation(s)
- Z J Xiang
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, and Key Laboratory of Strongly-coupled Quantum Matter Physics, Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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7
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Yang YF. Two-fluid model for heavy electron physics. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:074501. [PMID: 27214153 DOI: 10.1088/0034-4885/79/7/074501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The two-fluid model is a phenomenological description of the gradual change of the itinerant and local characters of f-electrons with temperature and other tuning parameters and has been quite successful in explaining many unusual and puzzling experimental observations in heavy electron materials. We review some of these results and discuss possible implications of the two-fluid model in understanding the microscopic origin of heavy electron physics.
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Affiliation(s)
- Yi-Feng Yang
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. Collaborative Innovation Center of Quantum Matter, Beijing 100190, People's Republic of China
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Cameron AS, Friemel G, Inosov DS. Multipolar phases and magnetically hidden order: review of the heavy-fermion compound Ce1-x La x B6. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:066502. [PMID: 27177075 DOI: 10.1088/0034-4885/79/6/066502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cerium hexaboride is a cubic f-electron heavy-fermion compound that displays a rich array of low-temperature magnetic ordering phenomena which have been the subject of investigation for more than 50 years. Its complex behaviour is the result of competing interactions, with both itinerant and local electrons playing important roles. Investigating this material has proven to be a substantial challenge, in particular because of the appearance of a 'magnetically hidden order' phase, which remained elusive to neutron-scattering investigations for many years. It was not until the development of modern x-ray scattering techniques that the long suspected multipolar origin of this phase was confirmed. Doping with non-magnetic lanthanum dilutes the magnetic cerium sublattice and reduces the f-electron count, bringing about substantial changes to the ground state with the emergence of new phases and quantum critical phenomena. To this day, Ce1-x La x B6 and its related compounds remain a subject of intense interest. Despite the substantial progress in understanding their behaviour, they continue to reveal new and unexplained physical phenomena. Here we present a review of the accumulated body of knowledge on this family of materials in order to provide a firm standpoint for future investigations.
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Curro NJ. Nuclear magnetic resonance in Kondo lattice systems. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:064501. [PMID: 27182054 DOI: 10.1088/0034-4885/79/6/064501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nuclear magnetic resonance has emerged as a vital tool to explore the fundamental physics of Kondo lattice systems. Because nuclear spins experience two different hyperfine couplings to the itinerant conduction electrons and to the local f moments, the Knight shift can probe multiple types of spin correlations that are not accessible via other techniques. The Knight shift provides direct information about the onset of heavy electron coherence and the emergence of the heavy electron fluid.
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Affiliation(s)
- Nicholas J Curro
- Department of Physics, University of California, Davis, CA 95616, USA
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10
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Wu YP, Zhao D, Wang AF, Wang NZ, Xiang ZJ, Luo XG, Wu T, Chen XH. Emergent Kondo Lattice Behavior in Iron-Based Superconductors AFe_{2}As_{2} (A=K, Rb, Cs). PHYSICAL REVIEW LETTERS 2016; 116:147001. [PMID: 27104721 DOI: 10.1103/physrevlett.116.147001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Indexed: 06/05/2023]
Abstract
Here, we experimentally study the origin of d-electron heavy fermion (HF) behavior in iron-based superconductors (FeSCs) AFe_{2}As_{2} (A=K, Rb, Cs). Nuclear magnetic resonance on ^{75}As reveals a universal coherent-incoherent crossover with a characteristic temperature T^{*}. Below T^{*}, a so-called "Knight shift anomaly" is first observed in FeSCs, which exhibits a scaling behavior similar to f-electron HF materials. Furthermore, the scaling rule also regulates the manifestation of magnetic fluctuation. These results undoubtedly support an emergent Kondo lattice scenario for the d-electron HF behavior, which qualifies the AFe_{2}As_{2} (A=K, Rb, Cs) as d-electron HF superconductors.
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Affiliation(s)
- Y P Wu
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - D Zhao
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - A F Wang
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - N Z Wang
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Z J Xiang
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - X G Luo
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - T Wu
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - X H Chen
- Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
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11
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Janoschek M, Das P, Chakrabarti B, Abernathy DL, Lumsden MD, Lawrence JM, Thompson JD, Lander GH, Mitchell JN, Richmond S, Ramos M, Trouw F, Zhu JX, Haule K, Kotliar G, Bauer ED. The valence-fluctuating ground state of plutonium. SCIENCE ADVANCES 2015; 1:e1500188. [PMID: 26601219 PMCID: PMC4646783 DOI: 10.1126/sciadv.1500188] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/12/2015] [Indexed: 06/01/2023]
Abstract
A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium's magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.
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Affiliation(s)
- Marc Janoschek
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Pinaki Das
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Bismayan Chakrabarti
- Department of Physics and Astronomy and Center for Condensed Matter Theory, Rutgers University, Piscataway, NJ 08854–8019, USA
| | - Douglas L. Abernathy
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831–6475, USA
| | - Mark D. Lumsden
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831–6475, USA
| | | | | | - Gerard H. Lander
- European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany
| | | | - Scott Richmond
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Mike Ramos
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Frans Trouw
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Jian-Xin Zhu
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Kristjan Haule
- Department of Physics and Astronomy and Center for Condensed Matter Theory, Rutgers University, Piscataway, NJ 08854–8019, USA
| | - Gabriel Kotliar
- Department of Physics and Astronomy and Center for Condensed Matter Theory, Rutgers University, Piscataway, NJ 08854–8019, USA
| | - Eric D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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12
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Kang CJ, Choi HC, Kim K, Min BI. Topological Properties and the Dynamical Crossover from Mixed-Valence to Kondo-Lattice Behavior in the Golden Phase of SmS. PHYSICAL REVIEW LETTERS 2015; 114:166404. [PMID: 25955062 DOI: 10.1103/physrevlett.114.166404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Indexed: 06/04/2023]
Abstract
We have investigated temperature-dependent behaviors of electronic structure and resistivity in a mixed-valent golden phase of SmS, based on the dynamical mean-field-theory band-structure calculations. Upon cooling, the coherent Sm 4f bands are formed to produce the hybridization-induced pseudogap near the Fermi level, and accordingly the topology of the Fermi surface is changed to exhibit a Lifshitz-like transition. The surface states emerging in the bulk gap region are found to be not topologically protected states but just typical Rashba spin-polarized states, indicating that SmS is not a topological Kondo semimetal. From the analysis of anomalous resistivity behavior in SmS, we have identified universal energy scales, which characterize the Kondo-mixed-valent semimetallic systems.
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Affiliation(s)
- Chang-Jong Kang
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Hong Chul Choi
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyoo Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
- c_CCMR, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - B I Min
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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13
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Field-induced density wave in the heavy-fermion compound CeRhIn₅. Nat Commun 2015; 6:6663. [PMID: 25798749 DOI: 10.1038/ncomms7663] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 02/18/2015] [Indexed: 11/08/2022] Open
Abstract
Strong electron correlations lead to a variety of distinct ground states, such as magnetism, charge order or superconductivity. Understanding the competitive or cooperative interplay between neighbouring phases is an outstanding challenge in physics. CeRhIn₅ is a prototypical example of a heavy-fermion superconductor: it orders anti-ferromagnetically below 3.8 K, and moderate hydrostatic pressure suppresses the anti-ferromagnetic order inducing unconventional superconductivity. Here we show evidence for a phase transition to a state akin to a density wave (DW) under high magnetic fields (>27 T) in high-quality single crystal microstructures of CeRhIn₅. The DW is signalled by a hysteretic anomaly in the in-plane resistivity accompanied by non-linear electrical transport, yet remarkably thermodynamic measurements suggest that the phase transition involves only small portions of the Fermi surface. Such a subtle order might be a common feature among correlated electron systems, reminiscent of the similarly subtle charge DW state in the cuprates.
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Abstract
Although the pairing glue for the attractive quasiparticle interaction responsible for unconventional superconductivity in heavy-electron materials has been identified as the spin fluctuations that arise from their proximity to a magnetic quantum critical point, there has been no model to describe their superconducting transition at temperature Tc that is comparable to that found by Bardeen, Cooper, and Schrieffer (BCS) for conventional superconductors, where phonons provide the pairing glue. Here we propose such a model: a phenomenological BCS-like expression for Tc in heavy-electron materials that is based on a simple model for the effective range and strength of the spin-fluctuation-induced quasiparticle interaction and reflects the unusual properties of the heavy-electron normal state from which superconductivity emerges. We show that it provides a quantitative understanding of the pressure-induced variation of Tc in the "hydrogen atoms" of unconventional superconductivity, CeCoIn5 and CeRhIn5, predicts scaling behavior and a dome-like structure for Tc in all heavy-electron quantum critical superconductors, provides unexpected connections between members of this family, and quantifies their variations in Tc with a single parameter.
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15
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Competition between heavy fermion and Kondo interaction in isoelectronic A-site-ordered perovskites. Nat Commun 2014; 5:5818. [DOI: 10.1038/ncomms6818] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 11/11/2014] [Indexed: 11/09/2022] Open
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16
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Abstract
Quantum critical behavior in heavy electron materials is typically brought about by changes in pressure or magnetic field. In this paper, we develop a simple unified model for the combined influence of pressure and magnetic field on the effectiveness of the hybridization that plays a central role in the two-fluid description of heavy electron emergence. We show that it leads to quantum critical and delocalization lines that accord well with those measured for CeCoIn5, yields a quantitative explanation of the field and pressure-induced changes in antiferromagnetic ordering and quantum critical behavior measured for YbRh2Si2, and provides a valuable framework for describing the role of magnetic fields in bringing about quantum critical behavior in other heavy electron materials.
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Cheng JG, Zhou JS, Yang YF, Zhou HD, Matsubayashi K, Uwatoko Y, MacDonald A, Goodenough JB. Possible Kondo physics near a metal-insulator crossover in the a-site ordered perovskite CaCu3Ir4O12. PHYSICAL REVIEW LETTERS 2013; 111:176403. [PMID: 24206506 DOI: 10.1103/physrevlett.111.176403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/05/2013] [Indexed: 06/02/2023]
Abstract
The A-site ordered perovskite (AA(3)')B(4)O(12) can accommodate transition metals on both A' and B sites in the crystal structure. Because of this structural feature, it is possible to have narrow-band electrons interacting with broadband electrons from different sublattices. Here we report a new A-site ordered perovskite (CaCu(3))Ir(4)O(12) synthesized under high pressure. The coupling between localized spins on Cu(2+) and itinerant electrons from the Ir-O sublattice makes Kondo-like physics take place at a temperature as high as 80 K. Results from the local density approximation calculation have confirmed the relevant band structure. The magnetization anomaly found at 80 K can be well rationalized by the two-fluid model.
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Affiliation(s)
- J-G Cheng
- Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, USA and Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan and Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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18
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Pines D. Finding New Superconductors: The Spin-Fluctuation Gateway to High Tc and Possible Room Temperature Superconductivity. J Phys Chem B 2013; 117:13145-53. [DOI: 10.1021/jp403088e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- David Pines
- Department
of Physics, UC Davis and UIUC, and the Santa Fe Institute, P.O. Box
576, Tesuque, New Mexico 87574, United States
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20
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Long range order and two-fluid behavior in heavy electron materials. Proc Natl Acad Sci U S A 2012; 109:E3067-73. [PMID: 23010926 DOI: 10.1073/pnas.1209609109] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The heavy electron Kondo liquid is an emergent state of condensed matter that displays universal behavior independent of material details. Properties of the heavy electron liquid are best probed by NMR Knight shift measurements, which provide a direct measure of the behavior of the heavy electron liquid that emerges below the Kondo lattice coherence temperature as the lattice of local moments hybridizes with the background conduction electrons. Because the transfer of spectral weight between the localized and itinerant electronic degrees of freedom is gradual, the Kondo liquid typically coexists with the local moment component until the material orders at low temperatures. The two-fluid formula captures this behavior in a broad range of materials in the paramagnetic state. In order to investigate two-fluid behavior and the onset and physical origin of different long range ordered ground states in heavy electron materials, we have extended Knight shift measurements to URu(2)Si(2), CeIrIn(5), and CeRhIn(5). In CeRhIn(5) we find that the antiferromagnetic order is preceded by a relocalization of the Kondo liquid, providing independent evidence for a local moment origin of antiferromagnetism. In URu(2)Si(2) the hidden order is shown to emerge directly from the Kondo liquid and so is not associated with local moment physics. Our results imply that the nature of the ground state is strongly coupled with the hybridization in the Kondo lattice in agreement with phase diagram proposed by Yang and Pines.
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