Crossed-ratchet effects and domain wall geometrical pinning

TL;DR

This paper investigates how the geometry of a medium influences domain wall motion and pinning, providing insights into optimizing crossed ratchet effects for controlling interface dynamics in patterned ferromagnetic films.

Contribution

It introduces a generic elastic model to analyze geometrical pinning and ratchet effects, combining calculations and simulations to guide design of effective interface control mechanisms.

Findings

Critical fields for depinning are anisotropic and depend on wall shape.

Geometrical configurations can be optimized to enhance ratchet effects.

The model predicts conditions for effective interface rectification.

Abstract

The motion of a domain wall in a two dimensional medium is studied taking into account the internal elastic degrees of freedom of the wall and geometrical pinning produced both by holes and sample boundaries. This study is used to analyze the geometrical conditions needed for optimizing crossed ratchet effects in periodic rectangular arrays of asymmetric holes, recently observed experimentally in patterned ferromagnetic films. Geometrical calculations and numerical simulations have been used to obtain the anisotropic critical fields for depinning flat and kinked walls in rectangular arrays of triangles. The aim is to show with a generic elastic model for interfaces how to build a rectifier able to display crossed ratchet effects or effective potential landscapes for controlling the motion of interfaces or invasion fronts.