Transport Properties of the "Excitonic Insulator": Thermal Conductivity

Abstract

The thermal conductivity of the excitonic insulator is calculated in the semimetallic limit. At low temperatures the main scattering mechanism is assumed to be due to impurities. Despite a recent claim of "super-thermal conductivity" of the system, which can be described as a condensate of electron-hole pairs, we find that the thermal conductivity is well behaved. It is shown that the thermal conductivity in the semimetallic limit of the underlying two-band model is almost identical to the thermal conductivity of a superconductor containing magnetic impurities as scatterers. The analogy stems from the fact that the thermodynamic properties in the two cases are similar, as was discussed recently.