Cooling electrons by magnetic-field tuning of Andreev reflection
  A solid-state cooling principle based on magnetic-field-driven tunable suppression of Andreev reflection in superconductor/two-dimensional electron gas nanostructures is proposed. This cooling mechanism can lead to very large heat fluxes per channel up to 10^4 times greater than currently achieved with superconducting tunnel junctions. This efficacy and its availability in a two-dimensional electron system make this method of particular relevance for the implementation of quantum nanostructures operating at cryogenic temperatures. 
F. Giazotto, F. Taddei, M. Governale, C. Castellana, R. Fazio, and F.   Beltram