Enhancing nanoparticle diffusion on a unidirectional domain wall magnetic ratchet

Abstract

The performance of nanoscale magnetic devices is often limited by the presence of thermal fluctuations, while in micro-nanofluidic applications the same fluctuations may be used to spread reactants or drugs. Here we demonstrate the controlled motion and the enhancement of diffusion of magnetic nanoparticles that are manipulated and driven across a series of Bloch walls within an epitaxially grown ferrite garnet film. We use a rotating magnetic field to generate a traveling wave potential that unidirectionally transports the nanoparticles at a frequency tunable speed. Strikingly, we find an enhancement of diffusion along the propulsion direction and a frequency dependent diffusion coefficient that can be precisely controlled by varying the system parameters. To explain the reported phenomena, we develop a theoretical approach that shows a fair agreement with the experimental data enabling an exact analytical expression for the enhanced diffusivity above the magnetically modulated periodic landscape. Our technique to control thermal fluctuations of driven magnetic nanoparticles represents a versatile and powerful way to programmably transport magnetic colloidal matter in a fluid, opening the doors to different fluidic applications based on exploiting magnetic domain wall ratchets.

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Cited by in corpus (10)

• Single-file transport in periodic potentials: The Brownian asymmetric exclusion process
• Memory effects in colloidal motion under confinement and driving
• Antiresonant driven systems for particle manipulation
• Mechanochemical Active Ratchet
• Enhanced dispersion in an oscillating array of harmonic traps
• Nonequilibrium transport and phase transitions in driven diffusion of interacting particles
• Depinning transition of self-propelled particles
• Nanoswimmers in a ratchet potential: Effects of a transverse rocking force
• Giant Vesicles with Encapsulated Magnetic Nanowires as Versatile Carriers, Transported via Rotating and Non-Homogeneous Magnetic Fields
• Controlling transport of underdamped particles in two-dimensional driven Bravais lattices