Binary crystals in two-dimensional two-component Yukawa mixtures.

The zero-temperature phase diagram of binary mixtures of like-charge particles interacting via a screened Coulomb pair potential is calculated as a function of composition and charge ratio. The potential energy obtained by a Lekner summation is minimized among a variety of candidate two-dimensional crystals. A wealth of different stable crystal structures is identified including A, B, AB(2), A(2)B, and AB(4) structures [A (B) particles correspond to large (small) charge.] Their elementary cells consist of triangular, square, or rhombic lattices of the A particles with a basis comprising various structures of A and B particles. For small charge asymmetry there are no intermediate crystals besides the pure A and B triangular crystals. The predicted structures are detectable in experiments on confined mixtures of like-charge colloids or dusty plasma sheets.