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Analysis of the paraconductivity in underdoped $La_{2-x}Sr_xCuO_4$ thin films using high magnetic fields

B. Leridon·J. Vanacken·T. Wambecq·V. V. Moshchalkov
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Abstract

The contribution of superconducting fluctuations to the conductivity, or paraconductivity is studied in the underdoped regime of $La_{2-x}Sr_xCuO_4$ cuprates. A perpendicular magnetic field up to 50 T is applied to suppress the superconductivity and obtain the normal state resistivity which is then used to calculate the paraconductivity. Surprisingly enough, it is consistent with a two-dimensional Aslamazov-Larkin (AL) regime of Gaussian fluctuations close to the critical temperature. At higher temperature, the paraconductivity shows a power-law decrease in temperature (as $T^{-α}$) as was previously shown for underdoped $YBa_2Cu_3O_{7-δ}$ and $Bi_2Sr_2CaCu_2O_{8+δ}$ samples. Our observations are not consistent with the existence of Kosterlitz-Thouless fluctuations. This tends to indicate that the superconducting pair amplitude is not already defined above $T_C$ in the pseudogap state.

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B. Leridon, J. Vanacken, T. Wambecq, V. V. Moshchalkov. 2007-02-28. Analysis of the paraconductivity in underdoped $La_{2-x}Sr_xCuO_4$ thin films using high magnetic fields. https://arxiv.org/abs/cond-mat/0611061

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