Stripe and Bubble Ratchets on Asymmetric Substrates

TL;DR

This paper investigates how anisotropic mesophase patterns like stripes and bubbles exhibit non-monotonic ratchet effects when driven by asymmetric substrates, with efficiency depending on morphology and drive parameters.

Contribution

It demonstrates the emergence of diverse ratchet behaviors in pattern-forming systems on asymmetric substrates, highlighting morphology-dependent rectification and potential for pattern sorting.

Findings

Stripe states show the strongest ratchet effect.

Large bubbles exhibit weak ratchet effects.

Small bubbles have strong, oscillating ratchet efficiency.

Abstract

We show that a variety of non-monotonic ratchet effects can arise when mesophase pattern-forming systems, which exhibit anisotropic crystal, stripe, and bubble reigmes, are coupled to one-dimensional asymmetric substrates under ac driving. The ratchet efficiency and direction of motion are determined by how well the mesophase morphology matches the periodicity and shape of the substrate. Stripe states that are aligned with the substrate show the strongest ratchet effect, large bubbles show a weak ratchet effect, and small bubbles show a strong ratchet effect with an efficiency that oscillates as a function of ac drive amplitude. We map out the different rectification phases as a function of the pattern morphology, substrate strength, and ac drive amplitude. The pronounced ratchet effects that we observe in some regimes can be exploited for pattern sorting in hard and soft matter systems.