From nonmetal to strange metal at the stripe-percolation transition in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>CuO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>
J. M. Tranquada, P. M. Lozano, Juntao Yao, Genda Gu, Qiang Li
Abstract
The nature of the normal state of cuprate superconductors continues to stimulate considerable speculation. Of particular interest has been the linear temperature dependence of the in-plane resistivity in the low-temperature limit, which violates the prediction for a Fermi liquid. We present measurements of anisotropic resistivity in ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ that confirm the strange-metal behavior for crystals with doped-hole concentration $p=x>{p}^{*}\ensuremath{\sim}0.19$ and contrast with the nonmetallic behavior for $p<{p}^{*}$. We propose that the changes at ${p}^{*}$ are associated with a first-order transition from doped Mott insulator to conventional metal; the transition appears as a crossover due to intrinsic dopant disorder. We consider results from the literature that support this picture; in particular, we present a simulation of the impact of the disorder on the first-order transition and the doping dependence of stripe correlations. Below ${p}^{*}$, the strong electronic interactions result in charge and spin stripe correlations that percolate across the ${\mathrm{CuO}}_{2}$ planes; above ${p}^{*}$, residual stripe correlations are restricted to isolated puddles. We suggest that the $T$-linear resistivity results from scattering of quasiparticles from antiferromagnetic spin fluctuations within the correlated puddles. This is a modest effect compared to the case at $p<{p}^{*}$, where the data suggest that there are no coherent quasiparticles in the normal state.