Evolution and control of oxygen order in a cuprate superconductor

Poccia, Nicola; Fratini, Michela; Ricci, Alessandro; Campi, Gaetano; Barba, Luisa; Vittorini-Orgeas, Alessandra; Bianconi, Ginestra; Aeppli, G.; Bianconi, A.

doi:10.1038/nmat3088

Cited by 157 publications

(215 citation statements)

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“…35 The variation of the critical temperature of the heterogeneous sample depends both on self-organization of oxygen-rich puddles and on the ordering of oxygen interstitials, as has been shown using thermal treatments controlling T c . 35 Using novel experimental microscopy, scanning nano x-ray diffraction, probing both the real and the k space, the formation of a granular phase in La 2 CuO 4+y has been discovered. Metallic heavily doped puddles, with ordered oxygen interstitials in the spacer layers, are embedded in an oxygen-poor background [34][35][36] at optimal doping.…”

Section: Introductionmentioning

confidence: 94%

“…[10][11][12] Superoxygenated La 2 CuO 4+y , y > 0.08, provides an ideal case to study the phase separation in the optimum doping regime and the role of ordering of oxygen interstitials (O i 's). [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.…”

Section: Introductionmentioning

confidence: 99%

“…35 Using novel experimental microscopy, scanning nano x-ray diffraction, probing both the real and the k space, the formation of a granular phase in La 2 CuO 4+y has been discovered. Metallic heavily doped puddles, with ordered oxygen interstitials in the spacer layers, are embedded in an oxygen-poor background [34][35][36] at optimal doping. In the heavily doped grains the excess oxygen interstitials are ordered as shown in Fig.…”

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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Section: Introductionmentioning

confidence: 94%

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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“…This has raised the importance of the structural topology for controlling the T c max in these materials. Indeed, recently it has been argued that electronic inhomogeneity controlled by organization of defects, lattice distortions, interface states, nanoscale phase separation in the layered oxides has substantial influence in the superconducting properties of cuprates [4][5][6][7][8][9]. This appears to be common to all layered superconductors as diborides [10][11][12][13] and more recently pnictides [14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Soft x-ray absorption and high-resolution powder x-ray diffraction study of superconducting Ca La1−Ba1.75−La0.25+Cu3O system

Agrestini

Sanna

Zheng

et al. 2014

Journal of Physics and Chemistry of Solids

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“…To investigate the interplay between the CDW puddles and the quenched disorder, we studied the spatial distribution of oxygen defects. 14,16) shows T c variations, owing to the effect of the spatial organization of O i on superconductivity.…”

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confidence: 99%

Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor

Campi

Bianconi

Poccia

et al. 2015

Nature

297

309

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It has recently been established that the high temperature (high-Tc(between atomic and macroscopic scale). Here we report micro X-ray diffraction imaging of the spatial distribution of both the charge-density-wave 'puddles' (domains with only a few wavelengths) and quenched disorder in HgBa 2 CuO 4+y , the single layer cuprate with the highest T c , 95 kelvin [26][27][28] . We found that the charge-density-wave puddles, like the steam bubbles in boiling water, have a fat-tailed size distribution that is typical of selforganization near a critical point 19 . However, the quenched disorder, which arises from oxygen interstitials, has a distribution that is contrary to the usual assumed random, uncorrelated distribution 12, 13 . The interstitials-oxygen-rich domains are spatially anticorrelated with the charge-density-wave domains, leading to a complex emergent geometry of the spatial landscape for superconductivity. 2Although it is known that the incommensurate charge-density-wave (CDW) order in cuprates (copper oxides) is made of ordered, stripy, nanoscale puddles with an average of only 3-4 oscillations, information about the size distribution and spatial organization of these puddles has so far not been available. We present experiments that demonstrate that CDW puddles, have a complex spatial distribution and coexist with, but are spatially anticorrelated to, quenched disorder in HgBa 2 CuO 4+y (Hg1201). The sample we studied is a layered perovskite at optimum doping with oxygen interstitials y=0.12, tetragonal symmetry P4/mmm and a low misfit strain [14][15][16] . The X-ray diffraction (XRD) measurements (see Methods) show diffuse CDW satellites (secondary peaks surrounding a main peak) at q CDW =(0.23a*, 0.16c*), in the b*=0 plane and q CDW =(0.23b*, 0.16c*) in the a*=0 plane (where a*, b*, and c* are the reciprocal lattice units) around specific Bragg peaks, such as (1 0 8), below the onset temperature T CDW =240 K (see Fig. 1a). The component of the momentum transfer q CDW in the CuO 2 plane (0.23a*) in this case is smaller than it is in the underdoped case (0.28a*) 5 . The temperature evolution of CDW-peak profile along a* (in the h direction; Fig. 1b) shows a smeared, glassy-like evolution below T CDW .The CDW-peak intensity reaches a maximum at T=100 K, followed by a drop associated with the onset of superconductivity at T=T c . We investigated the isotropic character of the CDW, in the a-b plane using azimuthal scans, as shown in Fig. 1c. We observed an equal probability of vertical and horizontally striped CDW puddles.Our main result is the discovery of the statistical spatial distribution of the CDW-puddle size and density throughout the sample, which shows an emergent complex network geometry for the superconducting phase. We performed scanning micro X-ray diffraction (SµXRD) measurements (see Methods) to extend the imaging of spatial inhomogeneity previously obtained by scanning tunneling microscopy [7][8][9] , from the surface to the bulk of the sample and from nanoscale to mesoscale spatial inh...

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Evolution and control of oxygen order in a cuprate superconductor

Cited by 157 publications

References 24 publications

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

Soft x-ray absorption and high-resolution powder x-ray diffraction study of superconducting Ca La1−Ba1.75−La0.25+Cu3O system

Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor

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