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Li N, Huang Q, Yue XY, Chu WJ, Chen Q, Choi ES, Zhao X, Zhou HD, Sun XF. Possible itinerant excitations and quantum spin state transitions in the effective spin-1/2 triangular-lattice antiferromagnet Na 2BaCo(PO 4) 2. Nat Commun 2020; 11:4216. [PMID: 32839456 PMCID: PMC7445251 DOI: 10.1038/s41467-020-18041-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 08/03/2020] [Indexed: 11/09/2022] Open
Abstract
The most fascinating feature of certain two-dimensional (2D) gapless quantum spin liquid (QSL) is that their spinon excitations behave like the fermionic carriers of a paramagnetic metal. The spinon Fermi surface is then expected to produce a linear increase of the thermal conductivity with temperature that should manifest via a residual value (κ0/T) in the zero-temperature limit. However, this linear in T behavior has been reported for very few QSL candidates. Here, we studied the ultralow-temperature thermal conductivity of an effective spin-1/2 triangular QSL candidate Na2BaCo(PO4)2, which has an antiferromagnetic order at very low temperature (TN ~ 148 mK), and observed a finite κ0/T extrapolated from the data above TN. Moreover, while approaching zero temperature, it exhibits series of quantum spin state transitions with applied field along the c axis. These observations indicate that Na2BaCo(PO4)2 possibly behaves as a gapless QSL with itinerant spin excitations above TN and its strong quantum spin fluctuations persist below TN.
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Affiliation(s)
- N Li
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA
| | - X Y Yue
- Institute of Physical Science and Information Technology, Anhui University, 230601, Hefei, Anhui, People's Republic of China
| | - W J Chu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Q Chen
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310-3706, USA
| | - X Zhao
- School of Physical Sciences, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA.
| | - X F Sun
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China. .,Institute of Physical Science and Information Technology, Anhui University, 230601, Hefei, Anhui, People's Republic of China.
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2
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Quantum electric-dipole liquid on a triangular lattice. Nat Commun 2016; 7:10569. [PMID: 26843363 PMCID: PMC4743005 DOI: 10.1038/ncomms10569] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/26/2015] [Indexed: 11/30/2022] Open
Abstract
Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics. In magnetic materials, geometry-defined competing interactions between spins combined with quantum fluctuations can present the possibility of quantum liquid states which do not order even as 0K is approached. Here, the authors present an analogue built from electric dipoles on a triangular lattice.
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Sacuto A, Gallais Y, Cazayous M, Méasson MA, Gu GD, Colson D. New insights into the phase diagram of the copper oxide superconductors from electronic Raman scattering. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:022502. [PMID: 23377173 DOI: 10.1088/0034-4885/76/2/022502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The mechanism of unconventional superconductivity is still unknown despite over 25 years passing since the discovery of high-T(c) cuprate superconductors by Bednorz and Muller (1986 Z. Phys. B 64 189). Here, we explore the cuprate phase diagram by electronic Raman spectroscopy and shed light on the superconducting state in hole-doped curates, namely, how superconductivity and the critical temperature T(c) are affected by the pseudogap.
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Affiliation(s)
- A Sacuto
- Laboratoire Matériaux et Phénomènes Quantiques (UMR 7162 CNRS), Université Paris Diderot-Paris 7, Bat. Condorcet, 75205 Paris Cedex 13, France.
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4
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Ghiringhelli G, Le Tacon M, Minola M, Blanco-Canosa S, Mazzoli C, Brookes NB, De Luca GM, Frano A, Hawthorn DG, He F, Loew T, Moretti Sala M, Peets DC, Salluzzo M, Schierle E, Sutarto R, Sawatzky GA, Weschke E, Keimer B, Braicovich L. Long-Range Incommensurate Charge Fluctuations in (Y,Nd)Ba2Cu3O6+x. Science 2012; 337:821-5. [PMID: 22798406 DOI: 10.1126/science.1223532] [Citation(s) in RCA: 265] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- G Ghiringhelli
- CNR-SPIN, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy.
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Mesaros A, Fujita K, Eisaki H, Uchida S, Davis JC, Sachdev S, Zaanen J, Lawler MJ, Kim EA. Topological Defects Coupling Smectic Modulations to Intra–Unit-Cell Nematicity in Cuprates. Science 2011; 333:426-30. [DOI: 10.1126/science.1201082] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- A. Mesaros
- Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, 2300 Leiden, Netherlands
- Laboratory for Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - K. Fujita
- Laboratory for Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - H. Eisaki
- Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - S. Uchida
- Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - J. C. Davis
- Laboratory for Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
- School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, UK
| | - S. Sachdev
- Department of Physics, Harvard University, Boston, MA 02138, USA
| | - J. Zaanen
- Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, 2300 Leiden, Netherlands
| | - M. J. Lawler
- Laboratory for Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902–6000, USA
| | - Eun-Ah Kim
- Laboratory for Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
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Sebastian SE, Harrison N, Lonzarich GG. Quantum oscillations in the high-Tc cuprates. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:1687-1711. [PMID: 21422021 DOI: 10.1098/rsta.2010.0243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We review recent progress in the study of quantum oscillations as a tool for uniquely probing low-energy electronic excitations in high-T(c) cuprate superconductors. Quantum oscillations in the underdoped cuprates reveal that a close correspondence with Landau Fermi-liquid behaviour persists in the accessed regions of the phase diagram, where small pockets are observed. Quantum oscillation results are viewed in the context of momentum-resolved probes such as photoemission, and evidence examined from complementary experiments for potential explanations for the transformation from a large Fermi surface into small sections. Indications from quantum oscillation measurements of a low-energy Fermi surface instability at low dopings under the superconducting dome at the metal-insulator transition are reviewed, and potential implications for enhanced superconducting temperatures are discussed.
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Affiliation(s)
- Suchitra E Sebastian
- Department of Physics, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK.
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Lawler MJ, Fujita K, Lee J, Schmidt AR, Kohsaka Y, Kim CK, Eisaki H, Uchida S, Davis JC, Sethna JP, Kim EA. Intra-unit-cell electronic nematicity of the high-T(c) copper-oxide pseudogap states. Nature 2010; 466:347-51. [PMID: 20631795 DOI: 10.1038/nature09169] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 05/04/2010] [Indexed: 11/10/2022]
Abstract
In the high-transition-temperature (high-T(c)) superconductors the pseudogap phase becomes predominant when the density of doped holes is reduced. Within this phase it has been unclear which electronic symmetries (if any) are broken, what the identity of any associated order parameter might be, and which microscopic electronic degrees of freedom are active. Here we report the determination of a quantitative order parameter representing intra-unit-cell nematicity: the breaking of rotational symmetry by the electronic structure within each CuO(2) unit cell. We analyse spectroscopic-imaging scanning tunnelling microscope images of the intra-unit-cell states in underdoped Bi(2)Sr(2)CaCu(2)O(8 +) (delta) and, using two independent evaluation techniques, find evidence for electronic nematicity of the states close to the pseudogap energy. Moreover, we demonstrate directly that these phenomena arise from electronic differences at the two oxygen sites within each unit cell. If the characteristics of the pseudogap seen here and by other techniques all have the same microscopic origin, this phase involves weak magnetic states at the O sites that break 90 degrees -rotational symmetry within every CuO(2) unit cell.
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Affiliation(s)
- M J Lawler
- Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902-6000, USA
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8
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Sonier JE. High-field μSR studies of superconducting and magnetic correlations in cuprates above T(c). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:203202. [PMID: 21393701 DOI: 10.1088/0953-8984/22/20/203202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The advent of high transverse field muon spin rotation (TF-μSR) has led to recent μSR investigations of the magnetic field response of cuprates above the superconducting transition temperature T(c). Here the results of such experiments on hole-doped cuprates are reviewed. Although these investigations are currently ongoing, it is clear that the effects of high field on the internal magnetic field distribution of these materials is dependent upon competition between superconductivity and magnetism. In La(2 - x)Sr(x)CuO(4) the response to the external field above T(c) is dominated by heterogeneous spin magnetism. However, the magnetism that dominates the observed inhomogeneous line broadening below x ∼ 0.19 is overwhelmed by the emergence of a completely different kind of magnetism in the heavily overdoped regime. The origin of the magnetism above x ∼ 0.19 is probably related to intrinsic disorder, but the systematic evolution of the magnetism with doping changes in the doping range beyond the superconducting 'dome'. In contrast, the width of the internal field distribution of underdoped Y Ba(2)Cu(3)O(y) above T(c) is observed to track T(c) and the density of superconducting carriers. This observation suggests that the magnetic response above T(c) is not dominated by electronic moments, but rather inhomogeneous fluctuating superconductivity. The spatially inhomogeneous response of Y Ba(2)Cu(3)O(y) to the applied field may be a means of minimizing energy, rather than being caused by intrinsic disorder.
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Affiliation(s)
- J E Sonier
- Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
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9
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Sebastian SE, Harrison N, Altarawneh MM, Mielke CH, Liang R, Bonn DA, Hardy WN, Lonzarich GG. Metal-insulator quantum critical point beneath the high Tc superconducting dome. Proc Natl Acad Sci U S A 2010; 107:6175-9. [PMID: 20304800 PMCID: PMC2851994 DOI: 10.1073/pnas.0913711107] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An enduring question in correlated systems concerns whether superconductivity is favored at a quantum critical point (QCP) characterized by a divergent quasiparticle effective mass. Despite such a scenario being widely postulated in high T(c) cuprates and invoked to explain non-Fermi liquid transport signatures, experimental evidence is lacking for a critical divergence under the superconducting dome. We use ultrastrong magnetic fields to measure quantum oscillations in underdoped YBa(2)Cu(3)O(6+x), revealing a dramatic doping-dependent upturn in quasiparticle effective mass at a critical metal-insulator transition beneath the superconducting dome. Given the location of this QCP under a plateau in T(c) in addition to a postulated QCP at optimal doping, we discuss the intriguing possibility of two intersecting superconducting subdomes, each centered at a critical Fermi surface instability.
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Affiliation(s)
- Suchitra E Sebastian
- Cavendish Laboratory, JJ Thomson Avenue, University of Cambridge, Cambridge CB3 OHE, UK.
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10
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Xia XJ, Ng TK. Thermal conductivity, Fermi pockets and superconductivity in underdoped cuprates. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:115703. [PMID: 21693926 DOI: 10.1088/0953-8984/21/11/115703] [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
The electronic contribution to thermal conductivity is studied in models of underdoped cuprates where the normal state has a pocketed Fermi surface with circumference ∼x (hole concentration) and the superconducting state is formed by opening a gap in the Fermi pocket. The physical consequences of the Fermi pocket are studied by comparing the thermal conductivity computed in four different models: (1) an ordinary d-wave superconductor with four Dirac Fermi points; (2) a normal metal with a pocketed Fermi surface; (3) a superconductor formed by spinon-holon binding in the t-J model; (4) a phenomenological d-wave Bardeen-Cooper-Schrieffer (BCS) superconductor with superconductivity formed by opening a gap on the pocketed Fermi surface. Our results suggest that thermal conductivity provides useful information to distinguish between different scenarios of the normal-to-superconducting transition in underdoped cuprates.
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Affiliation(s)
- Xiang-Jun Xia
- Department of Physics, Huazhong Normal University, Wuhan, Hubei 430079, People's Republic of China. Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China
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11
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LaForge AD, Padilla WJ, Burch KS, Li ZQ, Schafgans AA, Segawa K, Ando Y, Basov DN. Sum rules and interlayer infrared response of the high temperature YBa2Cu3Oy superconductor in an external magnetic field. PHYSICAL REVIEW LETTERS 2008; 101:097008. [PMID: 18851646 DOI: 10.1103/physrevlett.101.097008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Indexed: 05/26/2023]
Abstract
We present infrared magneto-optical measurements of the c-axis conductivity of YBa2Cu3Oy in both the underdoped (y=6.67 and 6.75) and optimally doped (y=6.95) regimes. We show that modest c-axis magnetic fields radically modify the condensate formation and restore conventional BCS-like energetics. Additionally, we demonstrate the pivotal role of interplane coherence in the anomalous high-energy contribution to the superfluid density.
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Affiliation(s)
- A D LaForge
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
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12
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Ando Y. Comment on "onset of a boson mode at the superconducting critical point of underdoped YBa2Cu3Oy". PHYSICAL REVIEW LETTERS 2008; 100:029701-029702. [PMID: 18232941 DOI: 10.1103/physrevlett.100.029701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Indexed: 05/25/2023]
Affiliation(s)
- Yoichi Ando
- Institute of Scientific and Industrial Research Osaka University Ibaraki, Osaka 567-0047, Japan
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13
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Sun XF, Ono S, Abe Y, Komiya S, Segawa K, Ando Y. Electronic inhomogeneity and breakdown of the universal thermal conductivity of cuprate superconductors. PHYSICAL REVIEW LETTERS 2006; 96:017008. [PMID: 16486505 DOI: 10.1103/physrevlett.96.017008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Indexed: 05/06/2023]
Abstract
We report systematic, high-precision measurements of the low-T (down to 70 mK) thermal conductivity kappa of YBa2Cu3O(y), La(2-x)Sr(x)CuO4, and Bi2Sr2CaCu2O(8+delta). Careful examinations of the Zn- and hole-doping dependences of the residual thermal conductivity kappa0/T, as well as the in-plane anisotropy of kappa0/T in Bi2Sr2CaCu2O(8+delta), indicate a breakdown of the universal thermal conductivity, a notable theoretical prediction for d-wave superconductors. Our results point to an important role of electronic inhomogeneities, which are not considered in the standard perturbation theory for thermal conductivity, in the underdoped to optimally doped regime.
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Affiliation(s)
- X F Sun
- Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan
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14
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Löfwander T, Fogelström M. Low-temperature thermal conductivity of superconductors with gap nodes. PHYSICAL REVIEW LETTERS 2005; 95:107006. [PMID: 16196957 DOI: 10.1103/physrevlett.95.107006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Indexed: 05/04/2023]
Abstract
We report a detailed analytic and numerical study of electronic thermal conductivity in d-wave superconductors. We compare theory of the crossover at low temperatures from T dependence to T(3) dependence for increasing temperature with recent experiments on YBa(2)Cu(3)O(7) in zero magnetic field for T approximately [0.04 K,0.4 K] by Hill et al. [Phys. Rev. Lett. 92, 027001 (2004)]. Transport theory, including impurity scattering and inelastic scattering within strong-coupling superconductivity, can consistently fit the temperature dependence of the data in the lower half of the temperature regime. We discuss the conditions under which we expect power-law dependences over wide temperature intervals.
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Affiliation(s)
- Tomas Löfwander
- Institut für Theoretische Festkörperphysik, Universität Karlsruhe, Germany
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15
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Sutherland M, Li SY, Hawthorn DG, Hill RW, Ronning F, Tanatar MA, Paglione J, Zhang H, Taillefer L, DeBenedictis J, Liang R, Bonn DA, Hardy WN. Delocalized fermions in underdoped cuprate superconductors. PHYSICAL REVIEW LETTERS 2005; 94:147004. [PMID: 15904097 DOI: 10.1103/physrevlett.94.147004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Indexed: 05/02/2023]
Abstract
Low-temperature heat transport was used to investigate the ground state of high-purity single crystals of the lightly doped cuprate YBa2Cu3O6.33. Samples were measured with doping concentrations on either side of the superconducting phase boundary. We report the observation of delocalized fermionic excitations at zero energy in the nonsuperconducting state, which shows that the ground state of underdoped cuprates is a thermal metal. Its low-energy spectrum appears to be similar to that of the d-wave superconductor, i.e., nodal. The insulating ground state observed in underdoped La2-xSrxCuO4 is attributed to the competing spin-density-wave order.
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Affiliation(s)
- Mike Sutherland
- Department of Physics, University of Toronto, Toronto, Ontario, Canada
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