Ultraefficient 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/mum(2) can be achieved, leading to electronic temperature reductions largely exceeding those obtained with existing superconductor-normal metal tunnel contacts. Half-metallic CrO2/Al bilayers are indicated as ideal candidates for the implementation of the device. (C) 2002 American Institute of Physics.