Resistivity saturation in an electron-doped cuprate

We report the observation of resistivity saturation in lightly doped ($x=0.08)$ as-grown samples of the electron-doped cuprate ${\mathrm{La}}_{2-x}{\mathrm{Ce}}_x{\mathrm{CuO}}_4$. The saturation occurs at resistivity values roughly consistent with the phenomenological Mott-Ioffe-Regel criterion once the low effective carrier density of these materials is included in the analysis. These results imply that, at least for light doping, the high-temperature metallic phase of these materials is not necessarily strange and may be understood as simply a low-density metal.

Figure 1

(a) $ab$-plane resistivity vs temperature for two as-grown $x=0.08$ LCCO samples. The dotted lines are estimates of the MIR limit calculated from Eq. (1) using $k_F={\left(3\pi n\right)}^{1/3}$, where $n$ is the carrier density of each sample, as determined from Hall measurements at 300 K. The values of $n$ and ${\rho }_{\text{MIR}}$ are given in Table 1. (b) The resistivity of another as-grown $x=0.08$ sample which is also seen to saturate at the highest measured temperature.

Figure 2

Resistivity traces of four as-grown $x=0.08$ samples, all of which exhibit resistivity saturation at room temperature. The carrier densities and estimates of ${\rho }_{\text{MIR}}$ for each sample are given in Table 1. The transparent marks on the right of the figure indicate ${\rho }_{\text{MIR}}$ for each sample for which the carrier density was measured.