Stable crystalline lattices in two-dimensional binary mixtures of dipolar particlesL. Assoud, R. Messina and H. Löwen
Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf - Universitätsstrasse 1, D-40225 Düsseldorf, Germany
received 15 June 2007; accepted in final form 13 September 2007; published November 2007
published online 10 October 2007
The phase diagram of binary mixtures of particles interacting via a pair potential of parallel dipoles is computed at zero temperature as a function of composition and the ratio of their magnetic susceptibilities. Using lattice sums, a rich variety of different stable crystalline structures is identified including AmBn structures. (A (B) particles correspond to large (small) dipolar moments.) Their elementary cells consist of triangular, square, rectangular or rhombic lattices of the A particles with a basis comprising various structures of A and B particles. For small (dipolar) asymmetry there are intermediate AB2 and A2B crystals besides the pure A and B triangular crystals. These structures are detectable in experiments on granular and colloidal matter.
82.70.Dd - Colloids.
61.50.Ah - Theory of crystal structure, crystal symmetry; calculations and modeling.
61.66.Dk - Alloys.
© Europhysics Letters Association 2007