Abstract
The observation of the quantum tunneling of magnetization has been accomplished in different multilayer systems of transition and rare earth metals. We have measured the time dependence of the thermoremanence magnetization up to temperaturesof 1.7 K. The tendency of the magnetic viscosity to have finite intercept at
T = 0 and/or the plateau in the
S(
T) values are the experimental manifestations of this new and fascinating effect.