Metal-Insulator Phase Transition in $\sf\small AC_{60}$: A Question of Dimensionality?

Abstract

The quasi 1D response of the electronically 3D AC₆₀ compounds is considered theoretically. We show that the condition for the appearance of an instability of the metallic phase is a considerable violation of the Fermi surface’s perfect nesting. We suggest that the different behaviour of RbC₆₀ and CsC₆₀ (both exhibit phase transitions) as compared to KC₆₀ (no instability) is rather due to \small differences in the band-filling of the electronically 3D systems than to a lowering of the dimensionality.