N. Barišić, Y. Li, G. Yu, X. Zhao, M. Dressel, A. Smontara, M. Greven
In the enigmatic lamellar cuprates, strong electronic correlations give rise to an insulating parent state from which superconductivity and eventually a Fermi-liquid-like metal emerge upon doping. At intermediate hole concentrations (p), the deviation from a linear-in-temperature planar resistivity (\rho $\propto$ T) upon cooling toward the superconducting state is associated with the opening of a 'pseudogap' in the antinodal regions of the Fermi surface. Contrary to common belief, we find in the pseudogap phase of structurally simple HgBa$_2$CuO$_{4+\delta}$ that \rho $\propto$ T$^2$, as in the putative Fermi-liquid state at high doping. By combining these results with prior work for other cuprates, we are able to obtain the fundamental resistance per copper-oxygen plaquette in both the linear (\rho_S = A_{1S} T) and quadratic (\rho_S = A_{2S} T$^2$) regimes, with A_{1S} $\propto$ A_{2S} $\propto$ 1/p. Any theory for the cuprates can now be benchmarked against this simple universal behavior of the planar resistivity.
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http://arxiv.org/abs/1207.1504
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