Field-dependent roughness of moving domain walls in a Pt/Co/Pt magnetic thin film

TL;DR

This study measures the roughness parameters of moving domain walls in a Pt/Co/Pt thin film, revealing how roughness amplitude varies with magnetic field and providing experimental data for theoretical models.

Contribution

It provides experimental values of the roughness exponent and amplitude for domain walls in a magnetic thin film, linking them to universal depinning and thermal behaviors.

Findings

Roughness exponent averaged at 0.74

Roughness amplitude increases as magnetic field decreases

Results enhance understanding of domain wall motion in disordered systems

Abstract

The creep motion of domain walls driven by external fields in magnetic thin films is described by universal features related to the underlying depinning transition. One key parameter in this description is the roughness exponent characterizing the growth of fluctuations of the domain wall position with its longitudinal length scale. The roughness amplitude, which gives information about the scale of fluctuations, however, has received less attention. Albeit their relevance, experimental reports of the roughness parameters, both exponent and amplitude, are scarce. We report here experimental values of the roughness parameters for different magnetic field intensities in the creep regime at room temperature for a Pt/Co/Pt thin film. The mean value of the roughness exponent is $\zeta = 0.74$, and we show that it can be rationalized as an effective value in terms of the known universal values corresponding to the depinning and thermal cases. In addition, it is shown that the roughness amplitude presents a significant increase with decreasing field. These results contribute to the description of domain wall motion in disordered thin magnetic systems.