On the bubble lattice generation in nonuniform pulse fields

Conclusion The dynamic equilibrium bubble domain lattices created by nonuniform magnetic field pulses were investigated in the region of pulse amplitudes where the domain structure behaved in the most regular way. The lattice formation was found possible in a rather narrow range of the bias field values (withinH _e<H<H _col) and in the area of the sample betweens ₂- ands ₁-boundaries. Detailed parameters on these boundaries (position, field and field gradient) were measured and calculated as functions of the bias field and the pulse field amplitude. The boundarys ₂ was understood as being the position in the sample where the total stray + applied field during the field pulses equalsH _e. A next magnetostatic calculation of the domain structure in the nonuniform field should give an appropriate theoretical formula fors ₁. High-speed photography has been used to record the immediate patterns of the domain structure both during a single field pulse and between the pulses. The obtained pictures made it possible to calculate the magnetic stray fields and stray field gradients when a simplified dipole model of the observed pattern was used. The attraction towards the wire has been compared with the repulsion due to the stray fields and their difference in the case of the equilibrium bubble lattice has been compared with the material coercivity term. The coercivity of the material was found to have very small influence on the translation of the domains during the process of the formation and spreading of the bubble lattice, which was attributed to the repetitive pulse component of the applied field.Dedicated to Jan Kaczér DrSc on the occasion of his 65-th birthday.The authors wish to thank L. Murtinová, P. Novotný and G. Vertésy for their helpful discussions, G. Vertésy for the ion implanted samples and L. Bodis and G. Battistig for taking part at the preliminary experiments.