THERMAL-CONDUCTIVITY OF SINGLE-CRYSTAL C-60

We report the first measurement of the thermal conductivity of single crystal C60. We observe that orientational disorder significantly reduces the thermal conductivity, evidenced by a large jump in the thermal conductivity at the 260 K orientational-order transition. The temperature and time dependences of the thermal conductivity below 260 K are shown to be described by a phenomenological model that involves thermally activated jumping motion between two nearly degenerate orientations, separated by an energy barrier of approximately 260 meV.