Magnetic induction and domain walls in magnetic thin films at remanence

TL;DR

This paper uses polarized neutron reflectometry to analyze magnetic domain walls in thin films, revealing how neutron refraction and scattering depend on magnetic induction, domain size, and wall properties.

Contribution

It introduces a detailed analysis of off-specular spin-flip scattering in thin films, distinguishing effects of magnetic induction from domain size influences.

Findings

Streaks in scattering maps are explained by neutron refraction at Néel walls.

Position of streaks depends solely on magnetic induction within domains.

Intensity of scattering depends on spin-flip probability and domain size.

Abstract

Magnetic domain walls in thin films can be well analyzed using polarized neutron reflectometry. Well defined streaks in the off-specular spin-flip scattering maps are explained by neutron refraction at perpendicular N\'{e}el walls. The position of the streaks depends only on the magnetic induction within the domains, whereas the intensity of the off-specular magnetic scattering depends on the spin-flip probability at the domain walls and on the average size of the magnetic domains. This effect is fundamentally different and has to be clearly distinguished from diffuse scattering originating from the size distribution of magnetic domains. Polarized neutron reflectivity experiments were carried out using a $^3$He gas spin-filter with a analyzing power as high as 96% and a neutron transmission of approx 35%. Furthermore, the off-specular magnetic scattering was enhanced by using neutron resonance and neutron standing wave techniques.