Magneto-Optical Imaging of Magnetic-Domain Pinning Induced by Chiral Molecules

TL;DR

This study demonstrates that chiral molecules can locally pin magnetic domains and alter magnetic properties in ferromagnetic thin films, revealing new ways to control magnetization using molecular chirality.

Contribution

It provides the first direct imaging evidence of chiral molecules inducing magnetic-domain pinning and axis rotation in ferromagnetic surfaces.

Findings

Chiral polypeptides strongly pin magnetic domains.

Local coercive field increases due to chiral molecules.

Magnetic easy axis rotates towards out-of-plane orientation.

Abstract

Chiral molecules have the potential for creating new magnetic devices by locally manipulating the magnetic properties of metallic surfaces. When chiral polypeptides chemisorb onto ferromagnets they can induce magnetization locally by spin exchange interactions. However, direct imaging of surface magnetization changes induced by chiral molecules was not previously realized. Here, we use Magneto-optical Kerr microscopy to image domains in thin films and show that chiral polypeptides strongly pin domains, increasing the coercive field locally. In our study, we also observe a rotation of the easy magnetic axis towards the out-of-plane, depending on the sample's domain size and the adsorption area. These findings show the potential of chiral molecules to control and manipulate magnetization and open new avenues for future research on the relationship between chirality and magnetization.