Jahn–Teller effect in the organic ferromagnet TDAE–C60 Original Research Article

We report on the measurements of the 13C NMR lineshape in the organic ferromagnet TDAE–C60 between room temperature and 4 K as well as on a simulation of the lineshape in this temperature interval. It is shown that the sudden increase in the inhomogeneous 13C NMR linewidth in the middle of the ferromagnetic phase can be explained by the freeze out of the pseudorotations of the axes of the Jahn–Teller distortions of the C60− ions. The correlation times for the Jahn–Teller dynamics of the C60− ions have been extracted from a comparison of experimental and simulated 13C NMR lineshapes. A strong correlation between spin ordering and orbital ordering has been found.