Reversal of domain walls drift direction in a low-frequency magnetic field in iron garnet crystals

Abstract

The reversal of domain walls (DWs) drift direction in (110) iron garnet plate with shape anisotropy with an increase of the amplitude of an alternating harmonic magnetic field was established experimentally. The harmonic magnetic field H = H0sin(2πft) (f = 3–1000 Hz, H0 up to 2.2⋅104 A/m) was applied perpendicular to the plane of the sample. The DW drift velocities and intensities of nucleation centers of magnetic dislocations (MDs) were measured. It is proposed that the reason for the reversal of direction of the DW drift is a change of direction of the gradient of demagnetizing fields in the sample with an increase of the external field amplitude. The change in configuration of an internal magnetic field is indicated by the experimentally established change in the activity of MD nucleation centers with the increase of the external field amplitude. A model is proposed in which direction and speed of DW drift are determined by magnetic field gradient in the sample.