Thermomagnetic transport properties of Nd 1.85 Ce 0.15 CuO 4 + δ films: Evidence for two types of charge carriers

We report measurements of the thermomagnetic properties of Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4{plus_minus}{delta}} thin films as a function of oxygen content. The variation of the Nernst coefficient with carrier doping{emdash}and its large magnitude{emdash}cannot be explained by a conventional single-carrier model. These measurements along with the variation of the Hall coefficient and the thermoelectric power with oxygen doping suggest that a two-carrier model might be suitable to describe the transport properties of these {ital electron-doped} cuprate superconductors. The ratio of the electrical and thermal Hall mobilities is presented as further evidence for the applicability of a two-carrier model. We finally show the correlation between the doping dependence of the Nernst coefficient and the magnetoresistance. {copyright} {ital 1997} {ital The American Physical Society}