Thermoelectric refrigeration at very low temperatures

It is shown that thermoelectric refrigeration might become an effective technique at or below a temperature of several mK. This is because the heat conduction due to the lattice vibrations becomes very small at these low temperatures. The thermoelectric material should have a high Debye temperature and a low carrier concentration, controlled so as to correspond to a Seebeck coefficient of a few hundred μV K^?1. One of the major difficulties in the achievement of low temperature thermoelectric refrigeration would, in fact, be the establishment of this optimum carrier concentration; it is suggested that it might be established through either an injection process or the application of a high magnetic field.