Effective two-dimensional thickness for the Berezinskii-Kosterlitz-Thouless-like transition in a highly underdoped La2xSrxCuO4

P. G. Baity, Xiaoyan Shi, Zhenzhong Shi, L. Benfatto, and Dragana Popović
Phys. Rev. B 93, 024519 – Published 25 January 2016

Abstract

The nature of the superconducting transition in highly underdoped thick films of La2xSrxCuO4 (x=0.07 and 0.08) has been investigated using the in-plane transport measurements. The contribution of superconducting fluctuations to the conductivity in zero magnetic field, or paraconductivity, was determined from the magnetoresistance measured in fields applied perpendicular to the CuO2 planes. Both the temperature dependence of the paraconductivity above the transition and the nonlinear current-voltage (IV) characteristics measured across it exhibit the main signatures of the Berezinskii-Kosterlitz-Thouless (BKT) transition. The quantitative comparison of the superfluid stiffness, extracted from the IV data, with the renormalization-group results for the BKT theory, reveals a large value of the vortex-core energy. This finding is confirmed by the analysis of the paraconductivity obtained using different methods. The results strongly suggest that the characteristic energy scale controlling the BKT behavior in this layered system corresponds to the superfluid stiffness of a few layers.

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  • Received 2 September 2015

DOI:https://doi.org/10.1103/PhysRevB.93.024519

©2016 American Physical Society

Authors & Affiliations

P. G. Baity1,2, Xiaoyan Shi1,2,*, Zhenzhong Shi1, L. Benfatto3, and Dragana Popović1,2,†

  • 1National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
  • 2Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
  • 3ISC-CNR and Dept. of Physics, Sapienza University of Rome, P.le A. Moro 5, 00185, Rome, Italy

  • *Present address: Department of Physics, University of Texas at Dallas, Richardson, TX 75080, USA.
  • dragana@magnet.fsu.edu

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Vol. 93, Iss. 2 — 1 January 2016

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