Period competition in a stripe domain structure subjected to a periodic field

Abstract

The behavior of a parallel array of stripe domains subjected to a periodic field was studied. Experiments were performed on a layer of single-crystal ferrimagnetic garnet (bubble material) featuring in zero field a periodic pattern of parallel stripe domains. The layer was applied to a magnetic tape on which a sinusoidal waveform was recorded. The garnet-tape distance, and hence the interaction strength, could be varied. The resulting domain patterns were observed in polarized light. We present results obtained for a recorded wavelength (66 μm) equal to six times the natural domain period (11 μm). The domain structure adapted itself by reducing the number of stripes, in particular by means of dislocation glide in the stripe array. This resulted in various modulated stripe patterns. The transitions between structures with different stripe numbers could be observed. These were achieved by local distortions of the parallel array around dislocations. The total energy of the garnet layer was calculated as the sum of magnetostatic, wall, and interaction energies for various interaction strengths. The equilibrium domain configuration could be deduced by minimizing the energy with respect to wall positions. The calculated modulated domain structures are in agreement with the observed one.