Large Thermoelectric Effects and Inelastic Scattering in Unconventional Superconductors

The thermoelectric coefficient eta(T) in unconventional superconductors is enhanced below Tc by intermediate strength impurity scattering that is intrinsically particle-hole asymmetric. We compute eta(T) for a strong-coupling d-wave superconductor and investigate the effects of inelastic scattering originating from electron-boson interactions. We show that eta(T) is severely suppressed at temperatures just below Tc by a particle-hole symmetric inelastic scattering rate. At lower temperatures inelastic scattering is frozen out and eta(T) recovers and regains its large amplitude. In the limit T->0, we have eta(T) ~ eta_0 T + O[T^3] , where the slope eta_0 contains information about the Drude plasma frequency, the details of impurity scattering, and the change in effective mass by electron-boson interactions. In this limit eta(T) can be used as a probe, complementary to the universal heat and charge conductivities, in investigations of the nature of nodal quasiparticles