Magnetic Contrast and Inclined 90° Domain Walls in Thick Iron Films

Abstract

A new structure of the magnetic 90° wall has been found in epitaxially grown (001) iron films with a thickness from 2000A to 7000A using a 1000 kV electron microscope. The 90° walls were observed as the images of different line widths and contrasts in Lorentz microscopy. The differences in line width and contrast appear in a selected area of a sample film and frequently along a 90° wall. From experiments of the Lorentz microscopy and deflection pattern using a sample tilting system, it is concluded that the 90° wall plane is inclined by different angles less than 45° from the film normal. A two-dimensional model of 90° wall is proposed and the wall energy E of the inclined wall is calculated. E has a broad minimum with respect to the inclination angle Δ ; E =4.0 erg/cm 2 at 14°< Δ <35° and =4.6 erg/cm 2 at Δ =0° and =52° for the 4000A iron film.