Superlubric-pinned transition of a two-dimensional solid dusty plasma under a periodic triangular substrate

TL;DR

This study explores the transition from superlubricity to pinning in a 2D dusty plasma on a periodic substrate, revealing how lattice mismatch and substrate depth influence sliding behavior and dynamical states.

Contribution

It demonstrates the superlubric-pinned transition in dusty plasma systems and characterizes how lattice mismatch and substrate depth affect the dynamical states.

Findings

Perfect lattice matching leads to pinned and moving states.

Lattice mismatch induces superlubricity with free sliding at shallow substrates.

In underdense systems, substrate depth controls the transition between dynamical states.

Abstract

The superlubric-pinned transition in the depinning dynamics of a two-dimensional (2D) solid dusty plasma modulated by 2D triangular periodic substrates is investigated using Langevin dynamical simulations. When the lattice structure of the 2D solid dusty plasma perfectly matches the triangular substrate, two distinctive pinned and moving ordered states are observed, as the external uniform driving force gradually increases from zero. When there is a mismatch between the lattice structure and the triangular substrate, however, on shallow substrates, it is discovered that all of the particles can slide freely on the substrate even when the applied driving force is tiny. This is a typical example of superlubricity, which is caused by the competition between the substrate-particle and particle-particle interactions. If the substrate depth increases further, as the driving force increases from zero, there are three dynamical states consisting of the pinned, the disordered plastic flow, and the moving ordered. In an underdense system, where there are fewer particles than potential well minima, it is found that the occurrence of the three different dynamical states is controlled by the depth of the substrate, which is quantitatively characterized using the average mobility.