NERNST EFFECT IN EPITAXIAL ND1.85CE.15CUO4 FILMS

We report measurements of thermally-driven flux motion (Nernst effect) in epitaxial Nd1.85Ce.15CuO4 films. It is found that, because of its relatively small H(c2) (6 Tesla) compared with other high T(c) materia ls such as YBCO and BSCCO, the Nernst coefficient in the mixed state o f Nd1.85Ce.15CuO4 depends much more strongly on sample temperature and applied magnetic field. The flux-line transport entropy, extracted fr om Nernst effect and resistivity measurements, has been found to quali tatively agree with the Maki's expression. As the applied magnetic fie ld exceeds H(c2), however, the observed normal-state Nernst effect is much larger than expected. This unusual behavior may be a two-band eff ect.