HIGH-PRESSURE EFFECTS ON THE QUANTUM TUNNELING OF MAGNETIZATION IN MN-12 ACETATE

The effect of high pressure on the quantum tunneling of magnetization (QTM) in the single-molecule magnet, Mn-12 acetate Mn12O12(O2CCH3)(16) (H2O)(4)); was Studied at 2.4 K. As the pressure is increased, the QT M is suppressed significantly with a slight high-field shift of the re sonance field that indicates an increase in the height of the potentia l barrier between the up- and down-spin states. At a maximum pressure of 1.0 GPa, the QTM rate decreases by 50%, while the resonance field i ncreases by 3.5%, The observed pressure dependence can he quantitative ly interpreted in terms of the thermally-activated QTM mechanism.