Cooperative Jahn-Teller effect in a 2D mesoscopic Cn -60 system with D 5D symmetry adsorbed on buffer layers using Ising EFT model

M. Abou Ghantous, E. A. Moujaes, J. L. Dunn, A. Khater

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Fullerene molecules adsorbed on surfaces often show macroscopic average distortions. As charged ions Cn -60 are known to be Jahn-Teller (JT) active, it is suggested that these distortions could be a manifestation of cooperative JT effects (CJTE) due to interactions between neighbouring fullerene ions. In order to understand the distortion properties it is necessary to take correlations between different distortions into account. However, this can't easily be done in the mean field approximation usually used to describe the CJTE. We therefore propose an alternative procedure to describe 2D mesoscopic islands of C60 ions in which a pseudo vector spin S is evoked to represent degenerate JT-distorted states when the quadratic JT coupling is considered. This approach is analogous to methods used for 2D magnetic systems. We then use the differential operator technique in effective field theory within the Ising approach. We include the effects of weak surface interactions and dynamic motion between equivalent distortions via terms equivalent to anisotropy and a transverse field in magnetism respectively. For distortions to D5d symmetry, we determine single site correlations as a function of temperature, the macroscopic average distortion describing a structural phase transition, and the isothermal response function. Phase diagrams are presented for relevant cases of the system parameters.

Original languageEnglish
Article number178
JournalEuropean Physical Journal B
Volume85
Issue number6
DOIs
Publication statusPublished - Jun 2012
Externally publishedYes

Fingerprint

Jahn-Teller effect
Ising model
Buffer layers
buffers
symmetry
Fullerenes
Ions
fullerenes
ions
differential operators
Magnetism
surface reactions
Phase diagrams
Anisotropy
Phase transitions
phase diagrams
anisotropy
Molecules
approximation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Cooperative Jahn-Teller effect in a 2D mesoscopic Cn -60 system with D 5D symmetry adsorbed on buffer layers using Ising EFT model. / Abou Ghantous, M.; Moujaes, E. A.; Dunn, J. L.; Khater, A.

In: European Physical Journal B, Vol. 85, No. 6, 178, 06.2012.

Research output: Contribution to journalArticle

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