DOPING DEPENDENCE OF NORMAL-STATE AND SUPERCONDUCTING-STATE TRANSPORT-PROPERTIES OF ND2-XCEXCUO4+ -Y THIN-FILMS/

The electric and thermomagnetic transport properties of an underdoped, an optimally doped, and an overdoped c-axis oriented, epitaxial Nd2-x CexCuO4+/-y thin film have been investigated in the temperature range from 4.2 K to 300 K and in magnetic fields up to 11 T oriented perpend icular to the CuO2 planes. In the normal state, the resistivity rho, H all coefficient R-H, and magnetoresistivity Delta rho/rho(B) can be de scribed quantitatively within a simple two-carrier model if the existe nce of an electronlike and a holelike band is assumed, where each of t he two groups of charge carriers is characterized by a temperature-ind ependent Hall coefficient. A corresponding analysis of the thermoelect ric effects appears to be more difficult since they depend on more sub tle details of the band structure and the scattering mechanisms. In th e superconducting regime, the critical field B-rho(T) determined from the shift of the resistive transition in an external magnetic field e xhibits a positive curvature. In contrast, an analysis of the fluctuat ion conductivity and the transport entropy of magnetic flux line S-phi consistently gives higher values for the upper critical field B,,(T). The fluctuation conductivity clearly exhibits two-dimensional scaling behavior, indicating that the quast-two-dimensional nature of the sin gle-layer compound Nd2-xCexCuO4+/-y might be responsible for the diffe rence between B-rho(T) and B-c2(T). The order of magnitude of S-phi i s consistent with the predictions of the Ginzburg-Landau theory. We de rived material parameters as B-c2(0), the in-plane coherence length xi (ab)(0), the Ginzburg-Landau parameter kappa, and the London penetrati on depth lambda(0). We also present experimental data on the Hall effe ct in the mixed state. [S0163-1829(98)00341-5].