Possible competitive electron- and hole-like conduction in the revived Nd1.82Ce0.18CuOy superconductors

Abstract

Thermoelectric power (S) studies on the nominally electron-doped Nd1.82-zSrzCe0.18CuOy (NSCCO) superconductor system in the temperature range 35 K to 250 K are reported here, S of the reduced z = 0.09 sample has negative sign, indicating electron conduction, and has small magnitude, showing high metallicity. The sign of S for the z = 0.18 sample however shows a cross-over below 75 K, from negative to positive, conflicting perhaps with electronic conduction, This sample on oxygenation exhibits broadened positive peak and apparently gets carrier concentration enhanced. There is seemingly a competition between electron and hole-like conduction in these co-doped compounds also.