Crossover from Universal Depinning to Free Domain-Wall Dynamics in Ultrathin Iron Garnet Films

TL;DR

This paper investigates the transition in magnetic domain wall behavior from disorder-controlled elastic pinning to texture-governed free motion in ultrathin iron garnet films, revealing the underlying crossover mechanism through experiments and simulations.

Contribution

It uncovers the disorder- and temperature-dependent crossover mechanism between pinned and free domain wall dynamics in ultrathin iron garnet films.

Findings

Identification of a disorder- and temperature-dependent precessional flow bridging the two regimes

Demonstration of exceptionally low pinning due to weak coupling and large correlation length

Validation of the crossover mechanism through experiments and Landau-Lifshitz-Gilbert simulations

Abstract

Magnetic domain walls display universal, disorder-controlled elastic dynamics at low drive, and texture-governed free motion at high drive. Here, we establish the crossover mechanism between these two regimes. Using experiments in ultrathin epitaxial iron garnet films and Landau-Lifshitz-Gilbert simulations, including disorder, thermal, and internal texture effects, we uncover a disorder- and temperature-dependent precessional flow that bridges pinned and free dynamics. We further demonstrate that the exceptionally low pinning in garnets arises from the weak coupling between domain walls and disorder, together with a correlation length that exceeds the wall width.