F. Lionti et al., THERMALLY ASSISTED MACROSCOPIC QUANTUM RESONANCE ON A SINGLE-CRYSTAL OF MN-12-ACETATE, Journal of applied physics, 81(8), 1997, pp. 4608-4610
Magnetization measurements have been performed on a single monocrystal
of the molecule Mn-12-acetate (Mn12Ac). Steps were observed in the hy
steresis loop for values of the applied field at which level crossings
of the collective spin states of each manganese clusters take place.
At these fields, the magnetization relaxes at short time scales, being
otherwise essentially blocked. This novel behavior is interpreted in
terms of resonant quantum tunneling of the magnetization from thermall
y activated energy levels. Hysteresis loop measurements performed for
different field orientations and alternating current (ac) susceptibili
ty experiments confirm this picture. (C) 1997 American Institute of Ph
ysics.