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Doiron-Leyraud N, Proust C, LeBoeuf D, Levallois J, Bonnemaison JB, Liang R, Bonn DA, Hardy WN, Taillefer L. Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor. Nature 2007; 447:565-8. [PMID: 17538614 DOI: 10.1038/nature05872] [Citation(s) in RCA: 780] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 04/18/2007] [Indexed: 11/09/2022]
Abstract
Despite twenty years of research, the phase diagram of high-transition-temperature superconductors remains enigmatic. A central issue is the origin of the differences in the physical properties of these copper oxides doped to opposite sides of the superconducting region. In the overdoped regime, the material behaves as a reasonably conventional metal, with a large Fermi surface. The underdoped regime, however, is highly anomalous and appears to have no coherent Fermi surface, but only disconnected 'Fermi arcs'. The fundamental question, then, is whether underdoped copper oxides have a Fermi surface, and if so, whether it is topologically different from that seen in the overdoped regime. Here we report the observation of quantum oscillations in the electrical resistance of the oxygen-ordered copper oxide YBa2Cu3O6.5, establishing the existence of a well-defined Fermi surface in the ground state of underdoped copper oxides, once superconductivity is suppressed by a magnetic field. The low oscillation frequency reveals a Fermi surface made of small pockets, in contrast to the large cylinder characteristic of the overdoped regime. Two possible interpretations are discussed: either a small pocket is part of the band structure specific to YBa2Cu3O6.5 or small pockets arise from a topological change at a critical point in the phase diagram. Our understanding of high-transition-temperature (high-T(c)) superconductors will depend critically on which of these two interpretations proves to be correct.
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52
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Ko E, Kim BJ, Kim C, Choi HJ. Strong orbital-dependent d-band hybridization and Fermi-surface reconstruction in metallic Ca2-xSrxRuO4. PHYSICAL REVIEW LETTERS 2007; 98:226401. [PMID: 17677865 DOI: 10.1103/physrevlett.98.226401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Indexed: 05/16/2023]
Abstract
We study the effects of RuO6 rotation on Ru 4d band structures in metallic Ca2-xSrxRuO4 (0.5 < or = x < or = 2) by first-principles electronic structure calculations. We show that the RuO6 rotation leads to the strong hybridization between dxy and dx2-y2 bands, resulting in orbital-dependent changes in the band structure. The dxy band near the Fermi level is significantly modified and thereby a severely reconstructed Fermi surface with nested sections appears at x=0.5. In contrast, the dyz and dzx bands are found to be insensitive to the rotational distortions induced by the Ca substitution. Our results imply that the progressive changes in the magnetic, optical, and thermal properties of Ca2-xSrxRuO4 are associated with the dxy band.
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Affiliation(s)
- Eunjung Ko
- Department of Physics and IPAP, Yonsei University, Seoul, 120-749, Korea
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53
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Valla T, Fedorov AV, Lee J, Davis JC, Gu GD. The Ground State of the Pseudogap in Cuprate Superconductors. Science 2006; 314:1914-6. [PMID: 17110536 DOI: 10.1126/science.1134742] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We present studies of the electronic structure of La(2-x)BaxCuO4, a system where the superconductivity is strongly suppressed as static spin and charge orders or "stripes" develop near the doping level of x = (1/8). Using angle-resolved photoemission and scanning tunneling microscopy, we detect an energy gap at the Fermi surface with magnitude consistent with d-wave symmetry and with linear density of states, vanishing only at four nodal points, even when superconductivity disappears at x = (1/8). Thus, the nonsuperconducting, striped state at x = (1/8) is consistent with a phase-incoherent d-wave superconductor whose Cooper pairs form spin-charge-ordered structures instead of becoming superconducting.
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Affiliation(s)
- T Valla
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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54
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Tanaka K, Lee WS, Lu DH, Fujimori A, Fujii T, Terasaki I, Scalapino DJ, Devereaux TP, Hussain Z, Shen ZX. Distinct Fermi-Momentum-Dependent Energy Gaps in Deeply Underdoped Bi2212. Science 2006; 314:1910-3. [PMID: 17114172 DOI: 10.1126/science.1133411] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We used angle-resolved photoemission spectroscopy applied to deeply underdoped cuprate superconductors Bi2Sr2Ca(1-x)YxCu2O8 (Bi2212) to reveal the presence of two distinct energy gaps exhibiting different doping dependence. One gap, associated with the antinodal region where no coherent peak is observed, increased with underdoping, a behavior known for more than a decade and considered as the general gap behavior in the underdoped regime. The other gap, associated with the near-nodal regime where a coherent peak in the spectrum can be observed, did not increase with less doping, a behavior not previously observed in the single particle spectra. We propose a two-gap scenario in momentum space that is consistent with other experiments and may contain important information on the mechanism of high-transition temperature superconductivity.
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Affiliation(s)
- Kiyohisa Tanaka
- Department of Physics, Department of Applied Physics, and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, CA 94305, USA
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55
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Gros C, Edegger B, Muthukumar VN, Anderson PW. Determining the underlying Fermi surface of strongly correlated superconductors. Proc Natl Acad Sci U S A 2006; 103:14298-301. [PMID: 16983075 PMCID: PMC1599958 DOI: 10.1073/pnas.0606219103] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The notion of a Fermi surface (FS) is one of the most ingenious concepts developed by solid-state physicists during the past century. It plays a central role in our understanding of interacting electron systems. Extraordinary efforts have been undertaken, by both experiment and theory, to reveal the FS of the high-temperature superconductors, the most prominent class of strongly correlated superconductors. Here, we discuss some of the prevalent methods used to determine the FS and show that they generally lead to erroneous results close to half-filling and at low temperatures, because of the large superconducting gap (pseudogap) below (above) the superconducting transition temperature. Our findings provide a perspective on the interplay between strong correlations and superconductivity and highlight the importance of strong coupling theories for the characterization and determination of the underlying FS in angle-resolved photoemission spectroscopy experiments.
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Affiliation(s)
- Claudius Gros
- *Institute for Theoretical Physics, J. W. Goethe University, 60438 Frankfurt, Germany
| | - Bernhard Edegger
- *Institute for Theoretical Physics, J. W. Goethe University, 60438 Frankfurt, Germany
- Department of Physics, City College of the City University of New York, New York, NY 10031; and
- Department of Physics, Princeton University, Princeton, NJ 08544
| | - V. N. Muthukumar
- Department of Physics, City College of the City University of New York, New York, NY 10031; and
| | - P. W. Anderson
- Department of Physics, Princeton University, Princeton, NJ 08544
- To whom correspondence should be addressed. E-mail:
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56
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Konik RM, Rice TM, Tsvelik AM. Doped spin liquid: Luttinger sum rule and low temperature order. PHYSICAL REVIEW LETTERS 2006; 96:086407. [PMID: 16606208 DOI: 10.1103/physrevlett.96.086407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Indexed: 05/08/2023]
Abstract
We analyze a model of two-leg Hubbard ladders weakly coupled by interladder tunneling. At half filling a semimetallic state with small Fermi pockets is induced beyond a threshold tunneling strength. The sign changes in the single electron Green's function relevant for the Luttinger sum rule now take place at surfaces with both zeros and infinities with important consequences for the interpretation of angle-resolved photoemission spectroscopy experiments. Residual interactions between electron and holelike quasiparticles cause a transition to long range order at low temperatures. The theory can be extended to small doping leading to superconducting order.
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Affiliation(s)
- R M Konik
- Department of Physics, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
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57
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Mannella N, Yang WL, Zhou XJ, Zheng H, Mitchell JF, Zaanen J, Devereaux TP, Nagaosa N, Hussain Z, Shen ZX. Nodal quasiparticle in pseudogapped colossal magnetoresistive manganites. Nature 2005; 438:474-8. [PMID: 16306987 DOI: 10.1038/nature04273] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Accepted: 09/19/2005] [Indexed: 11/09/2022]
Abstract
A characteristic feature of the copper oxide high-temperature superconductors is the dichotomy between the electronic excitations along the nodal (diagonal) and antinodal (parallel to the Cu-O bonds) directions in momentum space, generally assumed to be linked to the 'd-wave' symmetry of the superconducting state. Angle-resolved photoemission measurements in the superconducting state have revealed a quasiparticle spectrum with a d-wave gap structure that exhibits a maximum along the antinodal direction and vanishes along the nodal direction. Subsequent measurements have shown that, at low doping levels, this gap structure persists even in the high-temperature metallic state, although the nodal points of the superconducting state spread out in finite 'Fermi arcs'. This is the so-called pseudogap phase, and it has been assumed that it is closely linked to the superconducting state, either by assigning it to fluctuating superconductivity or by invoking orders which are natural competitors of d-wave superconductors. Here we report experimental evidence that a very similar pseudogap state with a nodal-antinodal dichotomous character exists in a system that is markedly different from a superconductor: the ferromagnetic metallic groundstate of the colossal magnetoresistive bilayer manganite La1.2Sr1.8Mn2O7. Our findings therefore cast doubt on the assumption that the pseudogap state in the copper oxides and the nodal-antinodal dichotomy are hallmarks of the superconductivity state.
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Affiliation(s)
- N Mannella
- Department of Physics, Applied Physics, and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, USA.
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58
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Gedik N, Langner M, Langer M, Orenstein J, Ono S, Abe Y, Ando Y. Abrupt transition in quasiparticle dynamics at optimal doping in a cuprate superconductor system. PHYSICAL REVIEW LETTERS 2005; 95:117005. [PMID: 16197037 DOI: 10.1103/physrevlett.95.117005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Indexed: 05/04/2023]
Abstract
We report time-resolved measurements of the photoinduced change in reflectivity, DeltaR, in the Bi2Sr2Ca(1-y)Dy(y)Cu2O8+delta (BSCCO) system of cuprate superconductors as a function of hole concentration. We find that the kinetics of quasiparticle decay and the sign of DeltaR both change abruptly where the superconducting transition temperature T(c) is maximal. These coincident changes suggest that a sharp transition in quasiparticle dynamics takes place precisely at optimal doping in the BSCCO system.
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Affiliation(s)
- N Gedik
- Physics Department, University of California, Berkeley, Berkeley, California, USA
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59
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Civelli M, Capone M, Kancharla SS, Parcollet O, Kotliar G. Dynamical breakup of the fermi surface in a doped Mott insulator. PHYSICAL REVIEW LETTERS 2005; 95:106402. [PMID: 16196948 DOI: 10.1103/physrevlett.95.106402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2004] [Revised: 05/12/2005] [Indexed: 05/04/2023]
Abstract
The evolution from an anomalous metallic phase to a Mott insulator within the two-dimensional Hubbard model is investigated by means of the cellular dynamical mean-field theory. We show that approaching the density-driven Mott metal-insulator transition the Fermi surface is strongly renormalized and the quasiparticle description breaks down in a very anisotropic fashion. Regions where the quasiparticles are strongly scattered (hot spots) and regions where the scattering rate is relatively weak (cold spot) form irrespective of whether the parent insulator has antiferromagnetic long-range order, while their location is not universal and is determined by the interplay of the renormalization of the scattering rate and the Fermi surface shape.
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Affiliation(s)
- M Civelli
- Physics Department and Center for Materials Theory, Rutgers University, Piscataway, New Jersey USA
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