Competing structures in 2D-trapped dipolar gases

TL;DR

This paper investigates how dipolar molecules in a 2D trap arrange themselves under competing influences of long-range dipolar interactions and an optical lattice, revealing a transition from square to triangular lattice structures.

Contribution

It provides a detailed analysis of the transition pathway between square and triangular arrangements in 2D dipolar gases under optical lattice confinement.

Findings

Identified the minimal-energy configurations at specific densities.

Mapped the transition pathway involving various lattice distortions.

Characterized the sequence of structural transformations during the transition.

Abstract

We study a system of dipolar molecules confined in a two-dimensional trap and subject to an optical square lattice. The repulsive long-range dipolar interaction $D/r^3$ favors an equilateral triangular arrangement of the molecules, which competes against the square symmetry of the underlying optical lattice with lattice constant $b$ and amplitude $V$. We find the minimal-energy states at the commensurate density $n = 1/b^2$ and establish the complete square-to-triangular transformation pathway of the lattice with decreasing $V$ involving period-doubled, solitonic, and distorted-triangular configurations.