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Theoretical model for the structural phase transition at the metal- insulator transition in polymerized KC60

B. Verberck·A. V. Nikolaev·K. H. Michel
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Abstract

The recently discovered structural transition in polymerized KC60 at about 50 K results in a doubling of the unit cell volume and accompanies the metal-insulator transition. Here we show that the (a+c,b,a-c) superstructure results from small orientational charge density waves along the polymer chains and concomitant displacements of the surrounding K+ ions. The effect is specific for the space group Pmnn of KC60 and is absent in Rb- and CsC60 (space group I2/m). The mechanism is relevant for the metal-insulator transition.

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B. Verberck, A. V. Nikolaev, K. H. Michel. 2002-11-06. Theoretical model for the structural phase transition at the metal- insulator transition in polymerized KC60. https://doi.org/10.1103/physrevb.66.165425

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