Two Fluids Formation in the Normal State of High-TC Superconductor

Abstract

Thermoelectric power (TEP) of high-TC superconductors has been investigated in a wide range of temperature (TC < T < 700 K) for La2−xSrxCuO4. For wide doping level from underdoping to heavily overdoping, TEP follows the linear-T dependence above the broad peak temperature, Tp. At high temperatures, however, TEP shows deviation from the linear-T dependence at a certain temperature Th, which is consistent with the pseudogap temperature. The systematic change of the TEP behavior is discussed in terms of the two fluids model of bound pairs and independent normal carriers.