Ultra-efficient Cooling in Ferromagnet-Superconductor Microrefrigerators
  A promising scheme for electron microrefrigeration based on ferromagnet-superconductor contacts is presented. In this setup, cooling power densities up to 600 nW/$\mu$m$^2$ can be achieved leading to electronic temperature reductions largely exceeding those obtained with existing superconductor-normal metal tunnel contacts. Half-metallic CrO$_2$/Al bilayers are indicated as ideal candidates for the implementation of the device. 
F. Giazotto, F. Taddei, R. Fazio, and F. Beltram