Thermoelectric power of a single-phase HgBa2Ca2Cu3Oy superconductor

An almost single-phase Hg-1223 superconductor was prepared and its thermoelectric power (TEP) was 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 critical temperature, Tc. 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 localised bound pairs and the delocalised 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. 16 refs.