Effects of grooving on domain wall structure in magnetic garnet

Experimental and computational techniques have been used to investigate the effects of grooves etched into the top surface of 1–2 μm thick films of magnetic bubble garnet on the surrounding magnetic structure. Partially grooved structures with groove depths ranging from 20%–75% of the film thickness are treated. Fields at a junction between two perpendicular grooves (cross-groove) are analyzed to determine whether such a structure can be used to confine a Vertical Bloch Line (VBL). Experimental data was collected using a Faraday effect microscope coupled with a laser for sampled photography. Computational data was collected through a simulation program that solved the Landau-Lifshitz-Gilbert equation on a Cartesian lattice using phenomenological material parameters. Grooves are shown to inhibit the expansion of a stripe domain located beneath it. The extent of the effects on the domain are directly related to the groove dimensions. Very high applied fields (>100 Oe for the cases studied) can be used to overcome the effects of groove, resulting in stripe domain break out or break in. Break-in has been shown to involve a split in the domain wall at the groove corner. The domain bounded by the upper section of the wall collapses immediately after formation. Cross-groove structures generate an in-plane field in the wall. This field is not uniform across the width of the wall, resulting in a field gradient. The ability to hold a VBL is dependent on the presence of this field gradient.