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

TL;DR

This paper maps the zero-temperature phase diagram of binary dipolar particle mixtures, revealing diverse stable crystalline structures depending on composition and magnetic susceptibility ratios, with potential experimental relevance.

Contribution

It provides a comprehensive theoretical analysis of stable crystalline lattices in binary dipolar mixtures, identifying new structures and their dependence on system parameters.

Findings

Multiple stable crystalline structures identified, including $A_mB_n$ types.

Intermediate $AB_2$ and $A_2B$ crystals found for small asymmetry.

Structures are experimentally detectable in granular and colloidal systems.

Abstract

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 $A_mB_n$ 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 $A_2B$ crystals besides the pure $A$ and $B$ triangular crystals. These structures are detectable in experiments on granular and colloidal matter.