Weak-coupling d-wave BCS superconductivity and unpaired electrons in overdoped La2−xSrxCuO4 single crystals

Yue Wang; Jing Yan; Lei Shan; Hai-Hu Wen; Yoichi Tanabe; Tadashi Adachi; Yoji Koike

doi:10.1103/PhysRevB.76.064512

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Weak-coupling d-wave BCS superconductivity and unpaired electrons in overdoped La2−xSrxCuO4 single crystals

Yue Wang, Jing Yan, Lei Shan, Hai-Hu Wen, Yoichi Tanabe, Tadashi Adachi, Yoji Koike

DOI 10.1103/PhysRevB.76.064512 · Physical Review B

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Abstract

The low-temperature specific heat (SH) of overdoped La2−xSrxCuO4 single crystals (0.178⩽x⩽0.290) has been measured. For the superconducting samples (0.178⩽x⩽0.238), the derived gap values (without any adjusting parameters) approach closely onto the theoretical prediction Δ0=2.14kBTc for the weak-coupling d-wave BCS superconductivity. In addition, the residual term γ(0) of SH at H=0 increases with x dramatically when beyond x∼0.22, and finally evolves into the value of a complete normal metallic state at higher doping levels, indicating a growing amount of unpaired electrons. We argue that this large γ(0) cannot be simply attributed to the pair breaking induced by the impurity scattering, instead the phase separation is possible.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	36	Pressure not reported	onset
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	30.5	Pressure not reported	onset
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	25	Pressure not reported	onset
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	19.5	Pressure not reported	onset
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.5	Pressure not reported	onset
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	36	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	30.5	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	25	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	19.5	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.5	Pressure not reported	unknown
Tl2Ba2CuO6+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown