Directional Locking in a 2D Yukawa Solid Modulated by a 2D Periodic Substrate

TL;DR

This study uses simulations to explore how a 2D dusty plasma solid interacts with a 2D square substrate, revealing directional locking effects and transitions between ordered and disordered states, relevant for experimental dusty plasma systems.

Contribution

It demonstrates the occurrence of directional locking in underdamped 2D dusty plasma solids modulated by a square substrate, expanding understanding of dynamical flow patterns.

Findings

Directional locking occurs near substrate symmetry directions.

Transitions between locked and unlocked states can be continuous or discontinuous.

Ordered and disordered flow states are observed depending on force direction.

Abstract

Directional depinning dynamics of a 2D dusty plasma solid modulated by a 2D square periodic substrate are investigated using Langevin dynamical simulations. We observe prominent directional locking effects when the direction of the external driving force is varied relative to the underlying square substrate. These locking steps appear when the direction of the driving force is close to the symmetry direction of the substrate, corresponding to the different dynamical flow patterns and the structures. In the conditions between the adjacent locking steps, moving ordered states are observed. Although the discontinuous transitions often occur between the locking steps and the non-locking portion, the continuous transitions are also found around the locking step associated with the disordered plastic flow close to its termini. Our results show that directional locking also occurs for underdamped systems, which could be tested experimentally in dusty plasmas modulated by 2D substrates.