Pressure dependence of the thermoelectric power of the iron-based high-Tc superconductor SmFeAsO0.85

Abstract

We have measured the thermoelectric power S of the iron-based superconductor SmFeAsO0.85 as a function of temperature at various pressures up to 1.1 GPa. The magnitude of thermoelectric power increases with decreasing temperature and exhibits a maximum at a characteristic temperature T* (∼110 K at ambient pressure), whereas the temperature dependence of the resistance shows metallic behavior. The superconducting transition temperature Tc and T* decrease monotonically with pressure. We discuss our results in terms of the effects of Fermi-surface nesting and orbit degeneracy in the new ironoxypnictides. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.