Elektronenoptische Untersuchung des magnetischen Streufeldes über (110)-Flächen prismatischer Nickel-Einkristalle

Abstract

An experiment is described that realizes a suggestion for measuring the magnetic stray field above the surface planes of ferromagnetic single crystals with defined shape and orientation. The cause of the deflection of the electrons in the resulting electron optical shadow-image is investigated and the problem is discussed, wether the deflections are due to “magnetic charges” of planes or lines. The experiments undertaken so far favour magnetic lines, i.e. the intersections of the Bloch-walls with the crystal surface, and make a quantitative evaluation of their leakage field possible. Calculations from our experimental data give a tangential field of about 3 Oe immediately at the surface between two Bloch-walls, and assuming line charges a normal field of about 100 Oe at a distance of 1μ above a 71°-Bloch-wall.