LOCAL ELECTRONIC STATES IN Bi2Sr2CaCu2O8+δ

Hashimoto, Akihiro; Kobatake, Yasuhiro; Ichikawa, Yo; Sugita, S.; Momono, N.; Oda, Masahiro; Ido, M.

doi:10.1142/9789812772879_0034

Cited by 3 publications

(7 citation statements)

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“…The dopant ions exert a significant electrostatic potential on the CuO 2 plane, and thus, unless the ions can be carefully arranged in a regular pattern, the mobile charge carriers experience a random potential. Recent scanning tunneling microscopy ͑STM͒ observations [1][2][3][4][5] clearly display that quenched randomness is crucial in determining the spatial modulations of the local density of states ͑LDOS͒.…”

Section: Introductionmentioning

confidence: 99%

From stripe to checkerboard ordering of charge-density waves on the square lattice in the presence of quenched disorder

2006

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We discuss the effects of quenched disorder on a model of charge density wave ͑CDW͒ ordering on the square lattice. Our model may be applicable to the cuprate superconductors, where a random electrostatic potential exists in the CuO 2 planes as a result of the presence of charged dopants. We argue that the presence of a random potential can affect the unidirectionality of the CDW order, characterized by an Ising order parameter. Coupling to a unidirectional CDW, the random potential can lead to the formation of domains with 90°relative orientation, thus tending to restore the rotational symmetry of the underlying lattice. We find that the correlation length of the Ising order can be significantly larger than the CDW correlation length. For a checkerboard CDW on the other hand, disorder generates spatial anisotropies on short length scales and, thus, some degree of unidirectionality. We quantify these disorder effects and suggest techniques for analyzing the spatially dependent local density of states data measured in scanning tunneling microscopy experiments.

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Section: Introductionmentioning

confidence: 99%

From stripe to checkerboard ordering of charge-density waves on the square lattice in the presence of quenched disorder

2006

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“…These reveal an intricate interplay between quasiparticles, vortices, order and disorder under the umbrella of high T c superconductivity. 15,16,17,18,19,20 The STM scans have been performed on large areas of freshly cleaved samples of Bi 2 Sr 2 CaCu 2 O 8+δ (BiSCCO) and Ca 2−x Na x CuO 2 Cl 2 (Na-CCOC) cuprate superconductors. Real space maps of LDOS show clear modulations which can be systematically studied in the Fourier space.…”

Section: Introductionmentioning

confidence: 99%

“…Our argument in favor of the incommensurate PWC is therefore largely phenomenological and is based on the following three observations. First, the checkerboard patterns in at least some experiments 17,19 have been reported to have period clearly different from 4 ionic lattice constants (the values range between 4.2 − 4.7a 0 ) implying incommensurate PWC. The mere existence of such an incommensurate PWC indicates that coupling to the lattice must be extremely weak even in the case when the PWC is commensurate.…”

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confidence: 99%

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Duality and the vibrational modes of a Cooper-pair Wigner crystal

Pereg-Barnea

Franz

2006

Phys. Rev. B

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When quantum fluctuations in the phase of the superconducting order parameter destroy the offdiagonal long range order, duality arguments predict the formation of a Cooper pair crystal. This effect is thought to be responsible for the static checkerboard patterns observed recently in various underdoped cuprate superconductors by means of scanning tunneling spectroscopy. Breaking of the translational symmetry in such a Cooper pair Wigner crystal may, under certain conditions, lead to the emergence of low lying transverse vibrational modes which could then contribute to thermodynamic and transport properties at low temperatures. We investigate these vibrational modes using a continuum version of the standard vortex-boson duality, calculate the speed of sound in the Cooper pair Wigner crystal and deduce the associated specific heat and thermal conductivity. We then suggest that these modes could be responsible for the mysterious bosonic contribution to the thermal conductivity recently observed in strongly underdoped ultraclean single crystals of YBa2Cu3O6+x tuned across the superconductor-insulator transition.

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“…One of the most striking is the observation, in some systems, of a form of local electronic ordering, especially around 1/8 hole doping. Indeed, recent scanning tunnelling microscopy/spectroscopy (STM/STS) experiments of underdoped Bi 2 Sr 2 CaCu 2 O 8+δ (BSCO) in the pseudogap state have shown evidence of energy-independent realspace modulations of the low-energy density of states (DOS) 17,18,19,20 with a spatial period close to four lattice spacings. A similar spatial variation of the electronic states has also been observed in the pseudogap phase of Ca 2−x Na x CuO 2 Cl 2 single crystals (x = 0.08 ∼ 0.12) by similar STM/STS techniques 21 .…”

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confidence: 99%

Bond-order-modulated staggered-flux phase of thetJmodel on a square lattice

Weber¹,

Poilblanc

Capponi

et al. 2006

Phys. Rev. B

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Motivated by the observation of inhomogeneous patterns in some high-Tc cuprate compounds, several variational Gutzwiller-projected wave-functions with built-in charge and bond order parameters are proposed for the extended t − J − V model on the square lattice at low doping. First, following a recent Gutzwiller-projected mean-field approach by one of us (Phys. Rev. B. 72, 060508(R) (2005)), we investigate, as a function of doping and Coulomb repulsion, the stability of the staggered flux phase with respect to small spontaneous modulations of squared unit cells ranging from 2 × 2 to √ 32× √ 32. It is found that a 4×4 bond-order (BO) modulation appears spontaneously on top of the staggered flux pattern for hole doping around 1/8. A related wave-function is then constructed and optimized accurately and its properties studied extensively using an approximation-free variational Monte Carlo scheme. Finally, the competition of the BO-modulated staggered flux wave-function w.r.t. the d-wave RVB wave-function or the commensurate flux state is investigated. It is found that a short range Coulomb repulsion penalizes the d-wave superconductor and that a moderate Coulomb repulsion brings them very close in energy. Our results are discussed in connection to the STM observations in the under-doped regime of some cuprates.

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LOCAL ELECTRONIC STATES IN Bi₂Sr₂CaCu₂O_8+δ

Cited by 3 publications

References 0 publications

From stripe to checkerboard ordering of charge-density waves on the square lattice in the presence of quenched disorder

From stripe to checkerboard ordering of charge-density waves on the square lattice in the presence of quenched disorder

Duality and the vibrational modes of a Cooper-pair Wigner crystal

Bond-order-modulated staggered-flux phase of thetJmodel on a square lattice

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