Single domain wall chirality studies using polarised neutrons

A single domain wall is created in a Permalloy film of macroscopic dimensions parallel to the surface by sending a current through the foil. With additional fields parallel to the film surface the position of the wall in the depth could be varied. Using 3-dimensional neutron polarization analysis the properties of this wall were studied, under which the thickness of this wall, the thickness as function of the depth of the wall in the film, the chirality and structure of left and right handed parts of the wall. By comparing simulations of the polarization matrix using different wall structures the Bloch model could be verified. The reversal of chirality was studied as function of a field parallel and anti-parallel to the magnetization in the center of the wall. A model was made about this reversal by nucleation that fits the observation. - Highlights: ► A domain wall of 12×3 cm2 was made by an electrical current in a Permalloy film. ► The thickness of the domain wall was determined by 3D neutron polarization. ► The Bloch wall nature of the wall was confirmed. ► The magnetic anisotropy could be determined from the domain wall thickness. ► The chirality of the wall and the chirality reversal in field was studied in detail.