Abstract
We have clarified the origin of the irreversibility involved in adiabatic demagnetization in the rotating frame (ADRF). The irreversibility is very high (~= 50\permil)in single in single quantum ADRF for 19F in CaF2. 7Li and 19f in LiF. Using an analysis based on the Provotorov's theory we conclude that the irreversibility is due to the thermal on the Provotorov's theory we conclude that the irreversibility is due to the thermal mixing between Zeeman and dipole systems in the demagnetization process.The conclusion is also supported by the experimental result that the reversibility becomes higher (or lower) when the dipole system is prepared at a positive (or negative) low temperature before ADRF. It is also shown that the characteristics of ADRF can be specified by a parameter T2D, where T2 is the free decay time and D the local Field in frequency units."
