ANOMALOUS NORMAL-STATE MAGNETOTHERMOPOWER OF ELECTRON-DOPED ND1.85CE0.15CUO4+DELTA CRYSTALS

The normal-state in-plane thermopower S of superconducting Nd1.85Ce0.1 5CuO4 (NCCO) crystals has been measured in magnetic fields B up to 9 T . When the magnetic field is parallel to the CuO2 planes, we find that S is B-independent, indicating the absence of spin entropy effects. A s B is oriented perpendicular to the CuO2 planes, a large negative mag netothermopower is found, suggesting an orbital effect which cannot be understood within existing models. A large T-dependent magnetothermop ower is also seen in an as-grown NCCO crystal when B is perpendicular to the CuO2 planes.