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Phase diagram of underdoped cuprate superconductors: Effects of Cooper-pair phase fluctuations

C. Timm, D. Manske, K. H. Bennemann

DOI 10.1103/PhysRevB.66.094515 · Physical Review B

T1

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Abstract

In underdoped cuprates fluctuations of the phase of the superconducting order parameter play a role due to the small superfluid density. We consider the effects of phase fluctuations assuming the exchange of spin fluctuations to be the predominant pairing interaction. Spin fluctuations are treated in the fluctuation-exchange approximation, while phase fluctuations are included by Berezinskii-Kosterlitz-Thouless theory. We calculate the stiffness against phase fluctuations, ns(ω)/m*, as a function of doping, temperature, and frequency, taking its renormalization by phase fluctuations into account. The results are compared with recent measurements of the high-frequency conductivity. Furthermore, we obtain the temperature T*, where the density of states at the Fermi energy starts to be suppressed, the temperature Tc*, where Cooper pairs form, and the superconducting transition temperature Tc, where their phase becomes coherent. We find a crossover from a phase-fluctuation-dominated regime with Tc∝ns for underdoped cuprates to a BCS-like regime for overdoped materials.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
GdBa2Cu3O7

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—Pressure not reportedunknown
Bi2Sr2CaCu2O8

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

100Pressure not reportedonset
La2-xSrxCuO4

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

40Pressure not reportedonset
La2-xSrxCuO4

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

90Pressure not reportedonset

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