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 ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$ that confirm the strange-metal behavior for crystals with doped-hole concentration $p=x>p^{*}\sim 0.19$ 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.

• Received 25 July 2023
• Revised 19 February 2024
• Accepted 17 April 2024

DOI:https://doi.org/10.1103/PhysRevB.109.184510