Andersen Group El.-Phon. QMC C60 GW Resistivity saturation

Orientational interaction

Based on the tight-binding parameters obtained from the band-structure calculations, the hopping energy between the molecules has been studied. This energy shows a strong dependence on the orientations of the C60 molecules ( Phys. Rev. Lett. 67, 3002 (1991)). Based on this, an Ising model (Phys. Rev. Lett. 70, 4142 (1993); I.I. Mazin et. al, Solid State Commun. 91, 497 (1994); Springer Series in Solid State Sciences 117, Springer, Berlin, 1993, p. 211.) was developed for A3C60, where the alkali ions restrict the C60 orientations and make two different orientations particular favorable. The interaction in this Ising model is antiferromagnetic and of the order J~100 K. The study of the phonon line shape seen in Raman scattering provides some support for a local "antiferromagnetic" correlation. Such support is also obtained from neutron scattering (S. Teslic, T. Egami, and J.E. Fischer, Phys. Rev. B 51 , 5973 (1995)).

Max-Planck Institut für Festkörperforschung
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Andersen Group Max-Planck-Institut für Festkörperforschung
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