Inhomogeneous superconductivity and the “pseudogap” state of novel superconductors

Kresin, Vladimir Z.; Morawitz, H.; Wolf, Stuart A.

doi:10.1093/acprof:oso/9780199652556.003.0011

Cited by 13 publications

(19 citation statements)

References 72 publications

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“…Our quantitative results should be tested against theories of composite, granular superconductors proposed for cuprates (10,14,15,25,(30)(31)(32)(55)(56)(57)(58)(59)(60)(61)(62). The X-ray data indicate that these theories must take into account not only the usual superconducting proximity effects, but also the effects of the strains the two components exert on each other.…”

Section: Discussionmentioning

confidence: 91%

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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Section: Discussionmentioning

confidence: 91%

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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“…Defects, as mobile oxygen interstitials, can control electronic inhomogeneity891011121314 and complex multi-scale phase separation15161718192021222324. Furthermore, inhomogeneity in the form of stripes have been shown to induce “shape resonances”2223 in the superconducting gaps in a multi-band superconductor24, which are type of Fano-Feshbach resonances at a BEC-BCS crossover.…”

mentioning

confidence: 99%

“…In high temperature superconductors (HTS), these networks of defects can influence essential properties such as the Fermi surface, pseudogap energy, spin density waves, charge density waves, and even the superconducting critical temperature. The strong tendency towards complex phase separation1415161718192021222324 can be used as advantage for developing new electronic devices. In fact, in some circumstances, defects order can be manipulated by scanning tunneling microscopy (STM)11, and/or by continuously exposing the sample to a UV or X-ray beam6710.…”

mentioning

confidence: 99%

Multiscale distribution of oxygen puddles in 1/8 doped YBa2Cu3O6.67

Ricci

Poccia

Campi

et al. 2013

Sci Rep

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Despite intensive research a physical explanation of high Tc superconductors remains elusive. One reason for this is that these materials have generally a very complex structure making useless theoretical models for a homogeneous system. Little is known on the control of the critical temperature by the space disposition of defects because of lack of suitable experimental probes. X-ray diffraction and neutron scattering experiments used to investigate y oxygen dopants in YBa2Cu3O6+y lack of spatial resolution. Here we report the spatial imaging of dopants distribution inhomogeneity in YBa2Cu3O6.67 using scanning nano X-ray diffraction. By changing the X-ray beam size from 1 micron to 300 nm of diameter, the lattice inhomogeneity increases. The ordered oxygen puddles size distribution vary between 6–8 nm using 1 × 1 μm2 beam, while it is between 5–12 nm with a fat tail using the 300 × 300 nm2 beam. The increased inhomogeneity at the nanoscale points toward a network of superconducting puddles made of ordered oxygen interstitials.

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“…The notion that competition between phases with charge ordering, spin ordering and superconductivity results in the formation of complex, heterogeneous structures, arranged as self-organised, fluctuating networks of "superstripes", has grown in popularity, fuelled by experimental evidence taken from a wide range of cuprate superconductors [2,3]. Intrinsic inhomogeneity resulting in phase separation is believed to be at the root of understanding the puzzling "pseudogap" state of underdoped cuprate superconductors above Tc [4]. It is found that in some regions of the material, Cooper pair formation occurs above the resistive transition temperature (Tc) as disconnected "puddles", leading to an anomalous diamag-netic signal.…”

Section: Introductionmentioning

confidence: 99%

Analytical microscopy of iron-based superconducting materials

Speller¹,

Mousavi²,

Dudin³

2015

Novel Superconducting Materials

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Inhomogeneity and phase separation in unconventional superconducting materials is a topic of increasing interest, as the competition between phases with different types of ordering is thought to play an important role in the emergence of the high temperature superconducting state. A wide range of experimental techniques are available for investigating the crystallography of these complex materials, however the majority are bulk probes. Here we briefly review some spatially resolved techniques that are being used to investigate phase separation in ironbased superconductors, with a focus on analytic Scanning Electron Microscopy techniques and synchrotron-based Photoelectron Microscopy.

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Inhomogeneous superconductivity and the “pseudogap” state of novel superconductors

Cited by 13 publications

References 72 publications

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

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

Multiscale distribution of oxygen puddles in 1/8 doped YBa2Cu3O6.67

Analytical microscopy of iron-based superconducting materials

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Inhomogeneous superconductivity and the “pseudogap” state of novel superconductors

Cited by 13 publications

References 72 publications

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

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

Multiscale distribution of oxygen puddles in 1/8 doped YBa2Cu3O6.67

Analytical microscopy of iron-based superconducting materials

Contact Info

Product

Resources

About

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

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