Anomalously sharp superconducting transitions in overdoped La_2−xSr_xCuO_4 films

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2010-12-16

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American Physical Society

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Abstract

We present measurements of ab-plane resistivity ρ_ab(T) and superfluid density (n_s∝λ^−2, λ=magnetic penetration depth) in La_2−xSr_xCuO_4 (LSCO) films. As Sr concentration x exceeds about 0.22, the superconducting transition sharpens dramatically, becoming as narrow as 200 mK near the super-to-normal-metal quantum critical point. At the same time, λ^−2(0) and transition temperature T_c decrease, and upward curvature develops in λ^−2(T). Given the sharp transitions, we interpret these results in the context of a homogeneous d-wave superconducting state, not a phase-separated state, with elastic scattering that is enhanced relative to underdoped LSCO due to weaker electron correlations.

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T. R. Lemberger et al, "Anomalously sharp superconducting transitions in overdoped La_2−xSr_xCuO_4 films," Physical Review B 82, no. 21 (2010), doi:10.1103/PhysRevB.82.214513