<I>In Situ</I> Lorentz Microscopy Observation of Displaced Chain Walls in Permalloy

Abstract

In situ investigation of displaced chain walls in 80 at% Ni Permalloy under applied in-plane magnetic field has been carried out by out-offocus methods of Lorentz electron microscopy. The magnetic flux in the plane of the film is schematically illustrated. The in-plane magnetic field applied to the foil is produced by a homemade magnetizing stage. By adjusting magnitude and direction of the electric current through the coils of the magnetizing stage, the magnetization reversal process of the magnetic domain wall has been in situ observed.

Characterization of magnetic domain walls using electron magnetic chiral dichroism

“…The Neel wall is spaced at regular intervals by short cross Bloch lines, denoted as 'cross ties', each terminating in a free end as shown in figure 1(a). Domain wall creeping of the circle-tie walls is connected with circular Bloch line movements and a variation of the main wall curvature [8,9]. …”

“…Most methods used for this purpose, such as Bitter powder technique, magneto-optical Kerr effect, Lorentz microscopy, electron holography, magnetic force microscopy and x-ray topography, have insufficient selectivity or spatial resolution to directly relate the microstructure and magnetic character of individual domain walls [5][6][7]. In our previous work, the movement of the circular Bloch line was studied by in situ Lorentz microscopy [8,9]. The magnetic contrast of Lorentz microscopy is based on the Lorentz force, which can only be used to identify the in-plane domains and Neel walls with magnetization orientation in the plane of a thin film.…”