Thermoelectric power of a single-phase HgBa2Ca2Cu3Oy superconductor

Abstract

An almost single-phase Hg-1223 superconductor has been prepared and its thermoelectric power (TEP) has been measured as a function of temperature. The sign of the TEP of this material is positive; the TEP shows a sharp increase just above the transition temperature and then decreases slowly; and the zero-crossing of the TEP coincides with the resistive transition temperature, T_c. Two models were applied to explain the anomalous TEP data. One model is based on the modified narrow-band Hubbard system with the additional Fermion contribution and the other is the phenomenological mixed-state model where the localized bound pairs and the delocalized carriers coexist in the normal state. Although both models can fit the semiconductor-like temperature dependence, the latter model takes into account the sharp increase just above the transition temperature.