Competition between electronic cooling and Andreev dissipation in a   superconducting micro-cooler
  We discuss very low temperature experiments on superconducting micro-coolers made of a double Normal metal - Insulator - Superconductor junction. We investigate with a high resolution the differential conductance of the micro-cooler as well as of additional probe junctions. There is an explicit crossover between the single quasi-particle current and the phase-coherent Andreev current. We establish a thermal model by considering the thermal contribution due to the Andreev current. The related increase of the electron temperature is discussed, including the influence of several parameters like the phase-coherence length or the tunnel junction transparency. 
Sukumar Rajauria (NEEL), Philippe Gandit (NEEL), F. W. J. Hekking   (PMMC), Bernard Pannetier (NEEL), Herv\'e Courtois (NEEL)