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Critical microwave-conductivity fluctuations across the phase diagram of superconducting La$_{2-x}$Sr$_x$CuO$_4$ thin films

Haruhisa Kitano·Takeyoshi Ohashi·Atsutaka Maeda·Ichiro Tsukada
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Abstract

We report a systematic study of the dynamic microwave conductivity near $T_c$ for La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) thin films with $x$=0.07 to 0.16. The strong frequency dependence of the phase stiffness together with scaling analysis of the ac fluctuating conductivity of superconductivity provide direct evidence for the 2D-XY behavior of nearly decoupled CuO$_2$ planes in underdoped LSCO ($x$=0.07 and 0.12). On the other hand, the critical exponents for slightly overdoped LSCO ($x$=0.16) were found to agree with those for the relaxational 3D-XY model, indicating that the universality class in LSCO is changed by hole doping. The implication of these results for the phase diagram of high-$T_c$ cuprates is discussed.

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Haruhisa Kitano, Takeyoshi Ohashi, Atsutaka Maeda, Ichiro Tsukada. 2006-01-12. Critical microwave-conductivity fluctuations across the phase diagram of superconducting La$_{2-x}$Sr$_x$CuO$_4$ thin films. https://doi.org/10.1103/physrevb.73.092504

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