Thermoelectric power of ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$${\mathrm{Ce}}_{\mathit{x}}$${\mathrm{CuO}}_4$ crystals

We report the in-plane thermopower S of ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$ ${\mathrm{Ce}}_{\mathit{x}}$ ${\mathrm{CuO}}_4$ (0.01≤x≤0.22) crystals for 4≤T≤300 K. In the weakly doped (x∼0.01–0.025) samples S is large and negative at high temperature, consistent with electron doping of the ${\mathrm{CuO}}_2$ planes, and approaches zero at low T. Crystals of superconducting and highly doped compositions (x≥0.15) show a small positive thermopower, with dS/dT<0. The thermopower of these samples is therefore surprisingly similar, in sign and T dependence, to that of the hole-doped cuprate superconductors.