Type-II magnetic domain contrasts caused by internal-magnetisation induced electron scattering anisotropy

TL;DR

This paper demonstrates that type-II magnetic domain contrast can be observed through electron scattering anisotropy caused by Lorentz force deflections, even when backscattering yields are identical, enabling detailed magnetic domain imaging.

Contribution

It introduces a novel method to visualize magnetic domains by exploiting electron-scattering anisotropy, independent of backscattering yield differences, and shows how to distinguish all in-plane magnetisation vectors.

Findings

Magnetic domain contrast arises from electron-scattering anisotropy due to Lorentz force.

All four in-plane magnetisation vectors can be distinguished using an electron backscatter diffraction detector.

A method to suppress topographic contrast on magnetic domain images is demonstrated.

Abstract

Previous studies have shown that type-II magnetic domain contrasts are caused by differences in the backscattering yields of magnetic domains of opposite magnetisation. Imaging the magnetic domains when the magnetisation vectors in the opposite-magnetisation domains are perpendicular to the tilt axis of the specimen has been considered impossible, because of the lack of change in the backscattering yields between the domains. However, we found that it is possible to observe the type-II magnetic domain contrast even in cases where the backscattering coefficients of the domains are the same. The contrast arises from the electron-scattering anisotropy created because of the deflection of the electron trajectories by the Lorentz force. We verify this by distinguishing all four possible in-plane magnetisation vectors on a Fe-Si(100) surface, using an electron backscatter diffraction detector as an arrya of electron detectors. The change in contrast between the magnetic domains, with respect to the location of a virtual electron detector, can provide information on the directions of the magnetisation vectors. A method to suppress the topographic contrast superimposed on the magnetic domain contrast is also demonstrated.