  133Cs and 13C-NMR have been used to study the electronic properties of the
polymerized phase of CsC60 at ambient and under hydrostatic pressure. The
salient result of this study is the finding of fluctuations in the local field
at 133Cs site which are independent of the applied pressure and due to
thermally activated changes in the local electronic environment of 133Cs
nuclei. We establish that the phase separation between magnetic and nonmagnetic
domains observed in the low temperature state at ambient pressure is the result
of a slowing down of these fluctuations likely related to polaronic charge
excitations on the polymers.
