Stable crystalline lattices in two-dimensional binary mixtures of dipolar particles

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 A m B n 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 AB 2 and A 2 B crystals besides the pure A and B triangular crystals. These structures are detectable in experiments on granular and colloidal matter.