Synchronous versus asynchronous transport of a paramagnetic particle in a modulated ratchet potential

TL;DR

This study investigates how a paramagnetic particle moves in a modulated ratchet potential, comparing synchronized and asynchronous transport regimes through experiments and a theoretical model, revealing a transition influenced by driving frequency.

Contribution

The paper provides a combined experimental and theoretical analysis of particle dynamics in a modulated magnetic ratchet, highlighting the transition between synchronized and sliding motion regimes.

Findings

Transition from phase-locked to sliding motion with increasing frequency

Good quantitative agreement between experimental data and the theoretical model

Thermal noise effects are incorporated into the particle dynamics interpretation

Abstract

We present a combined experimental and theoretical study describing the dynamical regimes displayed by a paramagnetic colloidal particle externally driven above a stripe-patterned magnetic garnet film. A circularly polarized rotating magnetic field modulates the stray field of the garnet film and generates a translating periodic potential which induces particle motion. Increasing the driving frequency, we observe a transition from a phase-locked motion with constant speed to a sliding dynamics characterized by a lower speed due to the loss of synchronization with the traveling potential. We explain the experimental findings with an analytically tractable theoretical model and interpret the particle dynamics in the presence of thermal noise. The model is in good quantitative agreement with the experiments.