Quantum phase interference and Néel-vector tunneling in antiferromagnetic molecular wheels.

The antiferromagnetic molecular wheel Fe 18 of 18 exchange-coupled Fe III ions has been studied by magnetic torque, magnetization, and inelastic neutron scattering. The combined data show that the low-temperature magnetism of Fe 18 is very accurately described by the Neel-vector tunneling (NVT) scenario, as unfolded by semiclassical theory. In addition, the magnetic torque as a function of applied field exhibits oscillations that reflect the oscillations in the NVT splitting with field due to quantum phase interference.