Possible competitive electron- and hole-like conduction in the revived Nd 1.82Ce 0.18CuO y superconductors

Abstract

Thermoelectric power ( S) studies on the nominally electron-doped Nd 1.82− z Sr z Ce 0.18CuO y (NSCCO) superconductor system in the temperature range 35 K to 250 K are reported are. 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 enhanced. There is seemingly a competition between electron and hole-like conduction in these co-doped compounds also.