Gap and pseudogap evolution within the charge-ordering scenario for superconducting cuprates

Benfatto, L.; Caprara, S.; Castro, C. Di

doi:10.1007/s100510070163

Cited by 114 publications

(126 citation statements)

References 12 publications

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“…[The in-plane lattice parameters are almost identical; therefore, the Te planes are essentially square (C 4 -symmetric), although the structure is fundamentally orthorhombic because of the glide plane between adjacent Te layers.] The survival of the C 4 rotational symmetry excludes the presence of precursor effects caused by nematic order, (e.g., intensively debated in the cuprates) (24,27), which would appear in B 1g symmetry.…”

Section: Resultsmentioning

confidence: 99%

Alternative route to charge density wave formation in multiband systems

Eiter

Lavagnini

Hackl

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

103

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Charge and spin density waves, periodic modulations of the electron, and magnetization densities, respectively, are among the most abundant and nontrivial low-temperature ordered phases in condensed matter. The ordering direction is widely believed to result from the Fermi surface topology. However, several recent studies indicate that this common view needs to be supplemented. Here, we show how an enhanced electron-lattice interaction can contribute to or even determine the selection of the ordering vector in the model charge density wave system ErTe 3 . Our joint experimental and theoretical study allows us to establish a relation between the selection rules of the electronic light scattering spectra and the enhanced electron-phonon coupling in the vicinity of band degeneracy points. This alternative proposal for charge density wave formation may be of general relevance for driving phase transitions into other brokensymmetry ground states, particularly in multiband systems, such as the iron-based superconductors.electron-phonon interactions | nonconventional mechanism | Raman spectroscopy | solid-solid phase transitions T he common view of charge density wave (CDW) formation was originally posed in the work by Kohn (1). Using Kohn's reasoning (1), the tendency to ordering is particularly strong in low dimensions, because the Fermi surface has parallel parts, referred to as nesting. This nesting leads to a divergence in the Lindhard susceptibility, determining the magnitude and direction of the ordering vector Q (2). This divergence in the electronic susceptibility is conveyed to the lattice by the electron-phonon coupling: a phonon softens to zero frequency at Q, and a static lattice distortion develops when the system enters the CDW state, a behavior known as the Kohn anomaly.However, several publications raise the question as to whether nesting alone is sufficient to explain the observed ordering direction Q (3-7), particularly in dimensions higher than 1D. A central question is whether the selection of the CDW ordering vector is always driven by an electronic instability or if the ordering vector could, instead, be determined by a lattice distortion driven by some other mechanism exploiting the role of the electron-phonon coupling. In the latter case, the selected ordering vector would not necessarily nest the Fermi surface. The importance of strongly momentum-dependent electron-phonon coupling on CDW formation was pointed out in refs. 3 and 4, where the relevance of the Fermi surface for determining the ordering vector was indeed found to decrease as the coupling strength increases. In a recent paper on inelastic X-ray scattering measurements on 2H-NbSe 2 , acoustic phonons were observed to soften to zero frequency over an extended region around the CDW ordering vector (8). The authors argue that this behavior is not consistent with a Kohn anomaly picture, where sharp dips are expected (8). Therefore, the phonon softening must be driven by another mechanism, which they identify as a wave vector-dependent e...

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Section: Resultsmentioning

confidence: 99%

Alternative route to charge density wave formation in multiband systems

Eiter

Lavagnini

Hackl

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

103

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“…As suggested by its different momentum dependence from its nodal counterpart, the antinodal pseudogap may have a different origin, which has been the subject for intense discussions in the literature [2][3][4][5][6][7][8][9] . Generally, as inferred from Supplementary Information, Fig.…”

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confidence: 99%

Energy gaps in the failed high-Tc superconductor La1.875Ba0.125CuO4

et al. 2008

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A central issue in high-T c superconductivity is the nature of the normal-state gap (pseudogap) 1 in the underdoped regime and its relationship with superconductivity. Despite persistent efforts, theoretical ideas for the pseudogap evolve around fluctuating superconductivity 2 , competing order 3-8 and spectral weight suppression due to many-body effects 9 . Recently, although some experiments in the superconducting state indicate a distinction between the superconducting gap and pseudogap 10-14 , others in the normal state, either by extrapolation from high-temperature data 15 The first high-T c superconductor discovered, La 2−x Ba x CuO 4 (LBCO), holds a unique position in the field because of an anomalously strong bulk T c suppression near x = 1/8. Right around this 'magic' doping level, scattering experiments by neutrons 18,19 and X-rays 20 find a static spin and charge (stripe) order. By itself, this observation raises a series of intriguing questions: whether the stripe order is a competing order that suppresses the superconductivity in LBCO-1/8; if the answer is positive, which aspect, the pairing strength or the phase coherence, is involved in the T c suppression and how this mechanism applies to other dopings or families. For our investigation of the 'ground-state' pseudogap, as defined in ref. 16, which ignores the residual superconductivity, its sufficiently high doping yet extremely low bulk T c (∼4 K) makes LBCO-1/8 an ideal system: especially for the small-gap measurement near the node, difficulties due to either the unscreened disorder potential, a problem for extremely low doping, or trivial thermal broadening, a problem above T c for higher doping, are circumvented.Whereas thermal effects require an extrapolation from high-temperature data to obtain the ground-state physics 15 , a direct measurement on LBCO-1/8 at low temperature has been made 16 . With experimental resolutions compromised to obtain sufficient signal to noise, a simple d-wave gap function is reported with no discernible nodal quasi-particles found. Given the importance of this issue, we have carried out an angle-resolved photoemission 21 study of LBCO-1/8 at T > T c with much improved resolutions in a measurement geometry favourable for the detection of nodal quasi-particles (see Fig. 1 and Supplementary Information, Section SI). Our data provide two important new insights. First, there is a well-defined nodal quasi-particle peak, suggesting nodal quasi-particles can exist in the stripe-ordered state. Second, there is a rich gap structure, suggesting the pseudogap physics is more elaborate than the simple d-wave version. In particular, a new kind of pseudogap, which is not smoothly connected to the usual one tied to the antinodal region, can exist in the nodal region when superconductivity is suppressed owing to the loss of phase coherence.As shown in Fig. 1, there exists a well-defined quasi-particle peak in the energy distribution curves (EDCs) at the Fermi crossing points (k F ) around the node. On dispersion towards the ant...

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“…D-wave density wave (dDW) for the pseudogap phase in high-T c cuprates has been proposed by several people. [33,34,35,36]. However, unlike these authors we do not consider the commensurate dDW with Z 2 -symmetry, which is a descendant of the flux phase [37].…”

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confidence: 99%

Gossamer superconductivity, new paradigm?

Won¹,

Haas

Maki

et al. 2005

Physica Status Solidi (b)

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Key words cuprate, d-wave superconductivity, d-wave density wave PACS 74.70.-b We shall review our recent works on d-wave density wave (dDW) and gossamer superconductivity (i.e. dwave superconductivity in the presence of dDW) in high-Tc cuprates and CeCoIn5. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn5 are manifestations of dDW. b) The phase diagram of high-Tc cuprates is understood in terms of mean field theory, which includes two order parameters ∆1 and ∆2, where one order paremeter is from dDW and the other from d-wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where ∆2/∆1 ≪ 1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high-Tc cuprate superconductors, the heavy-fermion superconductor CeCoIn5 and the organic superconductors κ-(ET)2Cu(NCS)2 and (TMTSF)2PF6.

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Gap and pseudogap evolution within the charge-ordering scenario for superconducting cuprates

Cited by 114 publications

References 12 publications

Alternative route to charge density wave formation in multiband systems

Alternative route to charge density wave formation in multiband systems

Energy gaps in the failed high-Tc superconductor La1.875Ba0.125CuO4

Gossamer superconductivity, new paradigm?

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