Susceptibility Discontinuity in Single CrystalC60

Abstract
Magnetization of a large single C60 crystal was measured as functions of applied field and temperature. At T=260 K, a discontinuity in susceptibility was observed. The relative change in total moment is 1.2%, independent of applied field to within experimental accuracy. This discontinuity is attributed to the change in the intramolecular geometry at the orientational order-disorder transition. This is the first experimental demonstration that the cooperative phase transition affects the magnetic susceptibility of a single molecule.