Two-dimensional discrete coulomb alloy

Yuqing Xiao, M. F. Thorpe

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

We study an (Formula presented) alloy on a two-dimensional triangular lattice. The ions A and B have different charges, with a background charge to ensure neutrality, and are constrained to lie at the discrete sites defined by a fixed triangular lattice. We study the various structures formed at different compositions x by doing computer simulations to find the lowest energy, using an energy minimization scheme, together with simulated annealing. Like ions try to avoid each other because of charge repulsion, which leads to structures, which are very different from those in a random alloy. At low concentrations, a triangular Wigner lattice is formed, which evolves continuously up to a concentration of (Formula presented) For higher concentrations, (Formula presented) there are long polymer chains, with occasional branches. We show that there is a symmetry about (Formula presented) which is the percolation point for nearest neighbors on the triangular lattice. At certain special stoichiometries, regular superlattices are formed, which usually have a slightly lower energy than a disordered configuration. The powder-diffraction patterns are calculated. The magnetic properties of this structure are also studied, and it is shown that the high-temperature susceptibility could be a useful diagnostic tool, in that it is very sensitive to the number of nearest-neighbor magnetic pairs. This work contributes to a better understanding of layered double hydroxides like (Formula presented)

Original languageEnglish (US)
Pages (from-to)277-285
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume59
Issue number1
DOIs
StatePublished - Jan 1 1999

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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