Large Thermoelectric Effects and Inelastic Scattering in Unconventional Superconductors

Journal article, 2006

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.