Comparison of 2-D Quantum and Thermal Critical Fluctuations of Underdoped Bi2Sr2CaCu2O8+δ with Ultrathin YBa2Cu3O7−δ
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This paper addresses two issues. Underdoped Bi-2212 has been shown to exhibit two-dimensional quantum fluctuations, with Tc vs. Ns(0) scaling qualitatively similar to ultrathin YBCO films that are 2-D by construction. The present paper shows that the quantitative difference in scaling is resolved by growing Bi-2212 films that are much smoother than previously used. Also, the absence of 2-D thermal critical behavior from the superfluid density of Bi-2212 films that exhibit 2-D quantum scaling is not likely due to an inhomogeneous Tc smearing out the 2-D thermal transition. Finally, we emphasize that there is as yet no consensus on the physics that drives the T-dependence of Ns at low to intermediate temperatures.
KeywordsSuperconductivity Quantum critical scaling Pulsed laser deposition Cuprates
- 3.Zuev, Y., Seog Kim, M., Lemberger, T.: Correlation between superfluid density and T c of underdoped YBa2Cu3O6+x near the superconductor-insulator transition. Phys. Rev. Lett. 95(13) (2005) Google Scholar
- 6.Yong, J., Hinton, M., McCray, A., Randeria, M., Naamneh, M., Kanigel, A., Lemberger, T.: Evidence of two-dimensional quantum critical behavior in the superfluid density of extremely underdoped Bi2Sr2CaCu2O8+x. Phys. Rev., B 85(18) (2012) Google Scholar
- 8.Broun, D., Huttema, W., Turner, P., Özcan, S., Morgan, B., Liang, R., Hardy, W., Bonn, D.: Superfluid density in a highly underdoped YBa2Cu3O6+y superconductor. Phys. Rev. Lett. 99(23) (2007) Google Scholar
- 9.Anukool, W., Barakat, S., Panagopoulos, C., Cooper, J.: Effect of hole doping on the London penetration depth in Bi2.15Sr1.85CaCu2O8+δ and Bi2.1Sr1.9Ca0.85Y0.15Cu2O8+δ. Phys. Rev., B 80(2) (2009) Google Scholar