Abstract

Magnetization measurements of molecular clusters [Mn-12](2-) with a spin ground state of S=10 show resonance tunneling at avoided energy level crossings. The observed oscillations of the tunnel probability as a function of the magnetic field applied along the hard anisotropy axis are due to topological quantum phase interference of two tunnel paths of opposite windings. [Mn-12](2-) is therefore the second molecular cluster exhibiting quantum phase interference. (C) 2002 American Institute of Physics.