Direct observation of domain wall surface tension by deflating or inflating a magnetic bubble

TL;DR

This paper presents direct experimental methods to measure magnetic domain wall surface energy by observing the collapse and pinning of magnetic bubbles, providing insights into magnetic interactions in thin films.

Contribution

It introduces novel experimental techniques for quantifying domain wall surface energy through bubble behavior, aiding the estimation of magnetic parameters like DMI and exchange stiffness.

Findings

Magnetic bubble collapse under Laplace pressure reveals surface energy effects.

Surface energy causes geometrically induced pinning during domain wall propagation.

Two new methods enable quantification of domain wall surface energy.

Abstract

The surface energy of a magnetic Domain Wall (DW) strongly affects its static and dynamic behaviours. However, this effect was seldom directly observed and many related phenomena have not been well understood. Moreover, a reliable method to quantify the DW surface energy is still missing. Here, we report a series of experiments in which the DW surface energy becomes a dominant parameter. We observed that a semicircular magnetic domain bubble could spontaneously collapse under the Laplace pressure induced by DW surface energy. We further demonstrated that the surface energy could lead to a geometrically induced pinning when the DW propagates in a Hall cross or from a nanowire into a nucleation pad. Based on these observations, we developed two methods to quantify the DW surface energy, which could be very helpful to estimate intrinsic parameters such as Dzyaloshinskii-Moriya Interactions (DMI) or exchange stiffness in magnetic ultra-thin films.