Questioning the Cuprate Paradigm: Absence of Superfluid Density Loss in Several Overdoped Cuprates I

J. L. Tallon; J. G. Storey; J. W. Loram; Jianlin Luo; C. Bernhard; I. Kokanović; J. R. Cooper

doi:10.1103/hkcc-xnkh

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Questioning the Cuprate Paradigm: Absence of Superfluid Density Loss in Several Overdoped Cuprates I

J. L. Tallon, J. G. Storey, J. W. Loram, Jianlin Luo, C. Bernhard, I. Kokanović, J. R. Cooper

DOI 10.1103/hkcc-xnkh · Physical Review Letters

T1

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Abstract

It is long established that overdoped cuprate superconductors experience a loss of superfluid density (SFD) with increasing doping, p, along with the decline in Tc. Such behavior is unconventional and suggests a depletion of the condensate by increasing pairbreaking or the growth of a second nonpairing channel. This led to a recent suggestion that the condensate arises from an incoherent charge channel, which progressively gives way with overdoping to a second, coherent nonpairing channel. Contra these ideas, we report analysis of the field-dependent electronic specific heat of several cuprates from which we find no apparent loss of SFD with overdoping. The SFD per CuO2 plaquette is found to rise progressively with overdoping from p toward (1+p), undiminished and much the same as the Hall number, thus implying that all available carriers contribute to the condensate. We suggest this could be the underlying intrinsic behavior for all cuprates. Our samples include (Y,Ca)Ba2Cu3O7−δ, Bi2Sr2CaCu2O8+δ, La2−xSrxCuO4, and Tl2Ba2CuO6, with the latter being the only exception. Our results signal a possible return to a more conventional picture.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Y0.8Ca0.2Ba2Cu3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	85	Pressure not reported	unknown
Y0.8Ca0.2Ba2Cu3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	54	Pressure not reported	unknown
Y0.8Ca0.2Ba2Cu3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	55	Pressure not reported	unknown
Bi2Sr2CaCu2O8+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Tl2Ba2CuO6+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	70	Pressure not reported	unknown
Tl2Ba2CuO6+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	53	Pressure not reported	unknown
Tl2Ba2CuO6+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	30	Pressure not reported	unknown
Tl2Ba2CuO6+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	24	Pressure not reported	unknown