Figure 5

(a,b) Layer structures of Samples I and II, respectively. (c,d) Magnetic domain expansion images overlaid with the snapshots taken at a specified time interval for Samples I and II, respectively. The blue arrow and red symbol represent directions of \(H_{x}\) and \(H_{z}\), respectively. The white symbols indicate the directions of magnetization. The brightest circle in the middle represents the initial magnetic domain. The yellow arrow indicates the direction of the \(v_{{{\text{DW}}}}\) measurement.