Dynamic conversion of magnetic bubble domain walls at megahertz frequencies in epitaxial garnet films

We have measured the circuit propagation characteristics of magnetic bubble domains in 15 different epitaxial films of Y1.9Sm0.1Ca1Ge1Fe4O12, using a TX propagation circuit with 28.8−μm period. For film thicknesses of 2 μm or less, reliable propagation was observed up to 1.7 MHz. Thicker films ceased to propagate reliably at frequencies as low as 0.5 MHz. Propagation failure is attributed to dynamic conversion of the bubble domain walls, and reasonably good quantitative agreement is shown between our measured critical frequencies and the critical frequencies calculated from a recently published model for dynamic conversion.