Department of Physics Papers
Document Type
Working Paper
Date of this Version
10-15-1993
Publication Source
Physical Review B
Volume
48
Issue
16
Start Page
12262
Last Page
12277
DOI
10.1103/PhysRevB.48.12262
Abstract
The mechanism of the orientational ordering of C60 in alkali-metal-doped fullerenes M3C60 is studied. Since the M-C60 (M=K,Rb) interactions cause the C60 molecules to assume one of two standard orientations, this model is equivalent to a generalized Ising model on a fcc lattice. The Ising interactions depend on two type of energies: (1) the direct interaction, i.e., the orientationally dependent part of interactions between nearest-neighboring C60 molecules (each carrying charge -3e), and (2) the band energy of the electrons transferred from M+ ions to the C603- ions. It is shown that the contribution to the pairwise interaction from the direct orientational interaction is ferromagnetic and dominantly nearest neighbor. However, contributions from the band (kinetic) energy of the conduction electrons are found to be antiferromagnetic for first- and third-nearest neighbors, ferromagnetic for second- and fourth-nearest neighbors, and negligible for further neighbors. The total first-neighbor interaction is probably antiferromagnetic. a non-negligible four-spin interaction is also obtained. The implication of these results for the orientational structure is discussed.
Recommended Citation
Yildirim, T., Hong, S., Harris, A., & Mele, E. J. (1993). Orientational Phases for M3C60. Physical Review B, 48 (16), 12262-12277. http://dx.doi.org/10.1103/PhysRevB.48.12262
Date Posted: 12 August 2015
This document has been peer reviewed.