Quantum phase interference (Berry phase) in single-molecule magnets of [Mn12]2−

Magnetization measurements of molecular clusters [Mn12]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. [Mn12]2− is therefore the second molecular cluster exhibiting quantum phase interference.