Domain-Wall Mobility in High-Uniaxial-Anisotropy Ferrites

Abstract

The dynamics of 180° domain walls has been studied in three hexagonal ferrite single crystals with a high uniaxial anisotropy. By means of an improved pulsed magnetic‐field technique and by analysis of the experimental method, we can observe the single‐wall mobility η just from the initial domain‐wall motion, i.e., for the lowest values of the internal field H_i. In the examined ferrimagnetic oxides the initial domain‐wall motion shows, as in cubic ferrites, a constant mobility η of the order of 10² cm/sec/Oe. Such a dynamical situation is followed by a more complex one, characterized by mobilities at least one order of magnitude lower. Moreover, we have indications that the domain‐wall apparent mass increases with increasing wall acceleration. We discuss the above‐mentioned phenomena in connection with the possible spin‐wave excitation during the wall movement.