A quantum phase transition driven by the electron lattice interaction gives high TC superconductivity

Bianconi, A.; Agrestini, S.; Bianconi, Ginestra; Castro, D. Di; Saini, N. L.

doi:10.1016/s0925-8388(00)01383-9

Cited by 62 publications

(87 citation statements)

References 40 publications

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“…The nonmagnetic (NM) total DOSs for La 16 Fig. 2(c)] show that the electron count is about the same for all three cases at approximately −1.0 eV below the respective E F 's.…”

Section: Resultsmentioning

confidence: 99%

“…[9][10][11][12][13][14] The defects inserted in the spacer layers to dope the copper oxide electronic structure are an additional source for the modulation of the heterogeneous electronic states near the Fermi level. 15 Particular attention has been addressed to oxygen interstitials that are mobile because of the misfit strain between the active and spacer layers 16 inducing a contraction of the Cu-O bonds. 17 Controlling their ordering by thermal treatments giant effects on superconductivity have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…[33][34][35][36] The O i 's in the rocksalt LaO layer are mobile; because of the large tensile strain in the spacer layers. This is due to the lattice misfit between different layers 16 of Cu-O bonds that is about 4% shorter than its equilibrium value of 1.97Å. 17 Therefore, by thermal treatments it is possible to induce their threedimensional ordering that has been shown to enhance the critical temperature to the highest value for La214.…”

Section: Introductionmentioning

confidence: 99%

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Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Jarlborg

Bianconi

2013

Phys. Rev. B

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Novel imaging methods show that the mobile dopants in optimum doped La 2 CuO 4+y (LCO) get self-organized, instead of randomly distributed, to form an inhomogeneous network of nanoscale metallic puddles with ordered oxygen interstitials interspersed with oxygen-depleted regions. These puddles are expected to be metallic, being far from half filling because of high dopant density, and to sustain superconductivity having a size in the range 5-20 nm. However, the electronic structure of these heavily doped metallic puddles is not known. In fact the rigid-band model fails because of ordering of dopants and supercell calculations are required to obtain the Fermi surface reconstruction. We have performed advanced band calculations for a large supercell La 16 Cu 8 O 32+N where N = 1 or 2 oxygen interstitials form rows in the spacer La 16 O 16+N layers intercalated between the CuO 2 layers as determined by scanning nano x-ray diffraction. The additional occupied states made by interstitial oxygen orbitals sit well below the Fermi level (E F ) and lead to hole doping as expected. The unexpected results show that in the heavily doped puddles the altered Cu(3d)-O(2p) band hybridization at E F induces a multiband electronic structure with the formation of multiple Fermi surface spots: (a) Small gaps appear in the folded Fermi surface, (b) three minibands cross E F with reduced Fermi energies of 60, 150, and 240 meV, respectively, (c) the density of states and band mass at E F show substantial increases, and (d) spin-polarized calculations show a moderate increase of antiferromagnetic spin fluctuations. All calculated features are favorable to enhance superconductivity; however, the comparison with experimental methods probing the average electronic structure of cuprates will require the description of the electronics of a network of multigap superconducting puddles.

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“…The nonmagnetic (NM) total DOSs for La 16 Fig. 2(c)] show that the electron count is about the same for all three cases at approximately −1.0 eV below the respective E F 's.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Jarlborg

Bianconi

2013

Phys. Rev. B

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“…[9] c) a spatial phase separation into two metallic phases made of distorted and undistorted stripes at the optimum doping regime [10] and two electronic states near the Fermi level. [11,12] d) the presence of a quantum critical point [13,14] in the two variables phase diagram:…”

Section: Introductionmentioning

confidence: 99%

Shape Resonance at a Lifshitz Transition for High Temperature Superconductivity in Multiband Superconductors

Innocenti

Valletta²,

Bianconi

2010

J Supercond Nov Magn

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“…For many years the dominant theories of HTS have considered a stoichiometric CuO 2 layer and have neglected the key role of lattice effects (16,17), even if the ½CuO 2 ∞ layers are intercalated by a variety of defective oxide AO layers (A=La, Ba, Sr, Ca, Y, Hg or Rare earths) with a large tolerance factor (18) or misfit strain (19,20) and a large number of oxygen interstitials or defects. The lattice misfit induces tilting and corrugation of the ½CuO 2 ∞ layers and structural phase transitions going from I4∕mmm (high temperature tetragonal), Bmab, Pccn, and Fmmm (low temperature orthorhombic, LTO) to P4 2 ∕ncm (low temperature tetragonal) in systems like La 2 CuO 4 (21).…”

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confidence: 99%

Optimum inhomogeneity of local lattice distortions in La ₂ CuO _{4+
y}

Poccia

Ricci

Campi

et al. 2012

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

113

140

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Electronic functionalities in materials from silicon to transition metal oxides are, to a large extent, controlled by defects and their relative arrangement. Outstanding examples are the oxides of copper, where defect order is correlated with their high superconducting transition temperatures. The oxygen defect order can be highly inhomogeneous, even in optimal superconducting samples, which raises the question of the nature of the sample regions where the order does not exist but which nonetheless form the "glue" binding the ordered regions together. Here we use scanning X-ray microdiffraction (with a beam 300 nm in diameter) to show that for La 2 CuO 4þy , the glue regions contain incommensurate modulated local lattice distortions, whose spatial extent is most pronounced for the best superconducting samples. For an underdoped single crystal with mobile oxygen interstitials in the spacer La 2 O 2þy layers intercalated between the CuO 2 layers, the incommensurate modulated local lattice distortions form droplets anticorrelated with the ordered oxygen interstitials, and whose spatial extent is most pronounced for the best superconducting samples. In this simplest of high temperature superconductors, there are therefore not one, but two networks of ordered defects which can be tuned to achieve optimal superconductivity. For a given stoichiometry, the highest transition temperature is obtained when both the ordered oxygen and lattice defects form fractal patterns, as opposed to appearing in isolated spots. We speculate that the relationship between material complexity and superconducting transition temperature T c is actually underpinned by a fundamental relation between T c and the distribution of ordered defect networks supported by the materials. granular superconductors | multiband superconductivity in density wave metals | scale-free heterogeneity | imaging phase separation | X-ray illumination

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A quantum phase transition driven by the electron lattice interaction gives high TC superconductivity

Cited by 62 publications

References 40 publications

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Shape Resonance at a Lifshitz Transition for High Temperature Superconductivity in Multiband Superconductors

Optimum inhomogeneity of local lattice distortions in La ₂ CuO _{4+
y}

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A quantum phase transition driven by the electron lattice interaction gives high TC superconductivity

Cited by 62 publications

References 40 publications

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Shape Resonance at a Lifshitz Transition for High Temperature Superconductivity in Multiband Superconductors

Optimum inhomogeneity of local lattice distortions in La 2 CuO 4+ y

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Optimum inhomogeneity of local lattice distortions in La ₂ CuO _{4+
y}