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Correlation between superfluid density and Tc of underdoped YBa2Cu3O6+x near the superconductor-insulator transition

Yuri Zuev·Mun Seog Kim·Thomas R. Lemberger
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Abstract

We report measurements of the ab-plane superfluid density Ns (magnetic penetration depth, λ) of severely underdoped films of YBa2Cu3O6+x, with Tc's from 6 to 50 K. Tc is not proportional to Ns(0); instead, we find Tc ~ Ns^{1/2.3 +/- 0.4}. At the lowest dopings, Tc is as much as 5 times larger than the upper limit set by the KTB transition temperature of individual CuO2 bilayers.

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Yuri Zuev, Mun Seog Kim, Thomas R. Lemberger. 2004-10-06. Correlation between superfluid density and Tc of underdoped YBa2Cu3O6+x near the superconductor-insulator transition. https://doi.org/10.1103/physrevlett.95.137002

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