Normal-state resistivity measurements at high fields and low temperatures in electron-doped ${\mathrm{Pr}}_{2-x}{\mathrm{Ce}}_x{\mathrm{CuO}}_4$ thin films reveal an insulator-metal crossover near a doping level $x\approx 0.15$, similar to a previous report on hole-doped ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x{\mathrm{CuO}}_4$. The temperature dependence of the resistivity of insulatinglike samples is sublogarithmic, while for metallic samples (with $x=0.17\mathrm{}$) the resistivity is linear from 40 mK to 40 K. This surprising latter observation suggests an unusual contribution to the scattering processes at low temperature in these materials. We conclude that the ground state at $x=0.15\mathrm{}$, corresponding to the maximum transition temperature, is equivalent for hole- and electron-doped cuprates.

• Received 28 May 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.4720