Order by disorder in the antiferromagnetic Ising model on an elastic triangular lattice.

ABSTRACT: Geometrically frustrated materials have a ground-state degeneracy that may be lifted by subtle effects, such as higher-order interactions causing small energetic preferences for ordered structures. Alternatively, ordering may result from entropic differences between configurations in an effect termed order by disorder. Motivated by recent experiments in a frustrated colloidal system in which ordering is suspected to result from entropy, we consider in this paper the antiferromagnetic Ising model on a deformable triangular lattice. We calculate the displacements exactly at the microscopic level and, contrary to previous studies, find a partially disordered ground state of randomly zigzagging stripes. Each such configuration is deformed differently and thus has a unique phonon spectrum with

SUBMITTER: Shokef Y 

PROVIDER: S-EPMC3141946 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature