Hall effect and magnetoresistance in ${\mathrm{Nd}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_{4\mathrm{-}\mathrm{\delta }}$ films

The electrical transport properties of the cuprate superconductor ${\mathrm{Nd}}_{1.85}$ ${\mathrm{Ce}}_{0.15}$ ${\mathrm{CuO}}_{4\mathrm{-}\mathrm{\delta }}$ have been studied in the mixed state and in the normal conducting state by measuring the Hall voltage and the longitudinal voltage of an epitaxial thin film. A broadening of the resistive transition with increasing fixed magnetic field and a sign reversal of the Hall effect in the mixed state were observed. In the normal state, the zero-field resistivity shows a quadratic temperature dependence. Magnetoresistance measurements for T=102 and 55 K yield a ${\mathit{B}}^2$ dependence up to B=10 T without any saturation tendency. The normal-state Hall coefficient is temperature dependent with a sign change from negative to positive for decreasing temperature. The data can be interpreted within a two-band model.