
Approach to Absolute Zero 295
14.4.5 Cascade nuclear demagnetization
The race to the proximity of absolute zero is really like a relay race. For example,
in the case of paramagnetic adiabatic demagnetization one first used a helium bath
to cool to 1.2 K, which at one time was the lowest temperature achievable, and then
achieve mK temperature ranges.
Extending this concept, Knuuttila and coworkers [16] of the
μ
KI (microkelvin in-
vestigations) group of the Lounasmaa lab at Helsinki, reached the lowest temperature
ever in a Rhodium sample. In the first stage they used dilution refrigeration to reach
3 mK range. Then in the next stage they used adiabatic