Percolative phase separation in La2CuO4+? and La2?x Sr x CuO4

Kremer, Reinhard K.; Sigmund, E.; Hizhnyakov, V.; Hentsch, F.; Simon, A.; Müller, K. A.; Mehring, M.

doi:10.1007/bf01323723

Cited by 126 publications

(51 citation statements)

References 20 publications

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“…Several different ideas of a superconducting phase in cuprates attainable by some form of percolation between pairs, cluster or stripes are not new [21][22][23] . More recently, a percolating approach was suggested and supported by the microscopic model based on a spatial dependent critical temperature T c (r) due to intrinsic inhomogeneities like pair breakers or spatial dependence of the superconducting coupling constant proposed by Ovchinnikov et al 24 .…”

Section: Introductionmentioning

confidence: 99%

Theory for high-Tcsuperconductors considering inhomogeneous charge distribution

2003

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We propose a general theory for the critical and pseudogap temperatures Tc and T * dependence on the doping concentration for high-Tc oxides, taking into account the charge inhomogeneities in the CuO2 planes. Several recent experiments have revealed that the charge density ρ in a given compound (mostly underdoped) is intrinsic inhomogeneous with large spatial variations which leads to a local charge density ρ(r). These differences in the local charge concentration yield insulator and metallic regions, either in an intrinsic granular or in a stripe morphology. In the metallic region, the inhomogeneous charge density produces also spatial or local distributions which form Cooper pairs at a local superconducting critical temperatures Tc(r) and zero temperature gap ∆0(r). For a given compound, the measured onset of vanishing gap temperature is identified as the pseudogap temperature, that is, T * , which is the maximum of all Tc(r). Below T * , due to the distribution of Tc(r)'s, there are some superconducting regions surrounded by insulator or metallic medium. The transition to a coherent superconducting state corresponds to the percolation threshold among the superconducting regions with different Tc(r)'s. The charge inhomogeneities have been studied by recent STM/S experiments which provided a model for our phenomenological distribution. To make definite calculations and compare with the experimental results, we derive phase diagrams for the BSCO, LSCO and YBCO families, with a mean field theory for superconductivity using an extended Hubbard Hamiltonian. We show also that this novel approach provides new insights on several experimental features of high-Tc oxides.

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Section: Introductionmentioning

confidence: 99%

Theory for high-Tcsuperconductors considering inhomogeneous charge distribution

2003

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“…As it was mentioned, the chemically driven phase separation directly related to oxygen mobility, has been observed in the experiment performed by Kremer et al [9] on oxygenated La2CuO4+δ. Even stronger experimental evidence that the phase separation in oxygenated La2CuO4+δ is driven, at least partly, by superfluous oxygen chemistry, has been reported by Ahrens et al [14].…”

Section: Introductionmentioning

confidence: 66%

“…It was assumed, until now, that the phase separation was the direct consequence of high enough oxygen mobility in the system. Recently, experiments performed by Kremer et al [9,10] questioned in part this common opinion. From the experimental findings it has been confirmed [9], without any doubt, that the observed phase separation is a diffusion controlled process.…”

Section: Introductionmentioning

confidence: 95%

“…Recently, experiments performed by Kremer et al [9,10] questioned in part this common opinion. From the experimental findings it has been confirmed [9], without any doubt, that the observed phase separation is a diffusion controlled process. The problem concerns the particles which can carry out diffusive motions.…”

Section: Introductionmentioning

confidence: 95%

“…It seems that the role of the oxygen mobility in formation of the macroscopically separated phases is not finally clarified. It is known [9] for example that in the La2_xSrxCuO4 system the macroscopic phase separation has not been observed. This observation is directly connected with the fact that diffusion of Sr ions at the relevant temperature is negligibly small.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Studies of Electronic Phase Separation in High Temperature Superconductors

Szymczak

1994

Acta Phys. Pol. A

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Experimental research on macroscopic phase separation in La2Cu04+δ superconductor and photo-doped cuprates is reviewed. It is shown that the properties of the mixed-phase state strongly depend on the shape and size of the phase domains formed during the phase separation process. The interplay of magnetic and superconducting properties in the mixed-phase state is considered in details. The mechanisms driving the phase separation in Lae Cu04 and photo-doped materials are discussed in connection with presented experimental results.

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Supraleitung und Chemie

Simon

1997

Angewandte Chemie

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Percolative phase separation in La2CuO4+? and La2?x Sr x CuO4

Cited by 126 publications

References 20 publications

Theory for high-Tcsuperconductors considering inhomogeneous charge distribution

Theory for high-Tcsuperconductors considering inhomogeneous charge distribution

Experimental Studies of Electronic Phase Separation in High Temperature Superconductors

Supraleitung und Chemie

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