  We discuss the effect of the thermal environment on the low-temperature
response of the magnetization of uniaxial magnets to a time-dependent applied
magnetic field. At sufficiently low temperatures the staircase magnetization
curves observed in molecular magnets such as Mn_{12} and Fe_8 display little
temperature dependence. However the changes of the magnetization at each step
do not seem to be directly related to the probability for a quantum mechanical
nonadiabatic transition. In order to explain this deceptive apparent
nonadiabatic behavior, we study the quantum dynamics of the system in a thermal
environment and propose a relation between the observed magnetization steps and
the quantum mechanical transition probability due to the nonadiabatic
transition.
