Jr. Friedman et al., MACROSCOPIC MEASUREMENT OF RESONANT MAGNETIZATION TUNNELING IN HIGH-SPIN MOLECULES, Physical review letters, 76(20), 1996, pp. 3830-3833
We report the observation of steps at regular intervals of magnetic fi
eld in the hysteresis loop of a macroscopic sample of oriented Mn12O12
(CH3COO)(16)(H2O)(4) crystals. The magnetic relaxation rate increases
substantially when the field is tuned to a step. We propose that these
effects are manifestations of thermally assisted, field-tuned resonan
t tunneling between quantum spin states, and attribute the observation
of quantum-mechanical phenomena on a macroscopic scale to tunneling i
n a large (Avogadro's) number of magnetically identical molecules.