A pulsed electron spin resonance (ESR) study of tetrakis-dimethylamino
-ethylene (TDAE)-C60 has been performed between 30 K and 4.2 K. The te
mperature dependence of the phase memory time T(M) has been determined
. The ESR line is found to be homogeneously broadened above T(c) = 16
K and inhomogeneously broadened below T(c). The results are compatible
with the formation of polarized spin clusters below T(c) giving rise
to a local field distribution rather than with a classical ferromagnet
ic ordering.