Temperature Correction to Casimir-Lifshitz Free Energy at Low   Temperatures: Semiconductors
  The Casimir force and free energy at low temperatures has been the subject of focus for some time. We calculate the temperature correction to the Casimir-Lifshitz free energy between two parallel plates made of dielectric material possessing a constant conductivity at low temperatures, described through a Drude-type dielectric function. For the transverse magnetic (TM) mode such a calculation is new. A further calculation for the case of the TE mode is thereafter presented which extends and generalizes previous work for metals. A numerical study is undertaken to verify the correctness of the analytic results. 
Simen A. Ellingsen, Iver Brevik, Johan S. H{\o}ye, and Kimball A.   Milton