Bubble lattice formation in thick MnBi platelet by one-point nucleation

The dynamic domain formations in a single crystal MnBi platelet were examined under various external field strengths. Once the reverse domain is nucleated at one point of the saturated plate by pricking or external pulse field, the domain expands with various modes depending on the net field strength acting on the moving wall and forms various patterns. In a thick platelet, a bubble lattice is produced with no bias field, but it is suppressed by the external field; a radial stripe domain pattern or a spider web like pattern is formed depending on the field polarity. The phase velocity of the wall propagation during lattice formation was estimated as about 50m/sec by the pulse field method. This result brought us the important information about the truly complicated nature of the bubble lattice formation, i.e., the sequential process of the dynamic conversion, breakdown of velocity, static conversion, high speed propagation, and sharp deflection.