The bias field dependence of the velocity of bubble propagation by the domain drag effect was studied in a GdCoAu amorphous film. Bubbles in closehyphen;packed arrays were propagated by pulsing currents directly through a stripline of the material fabricated by photolithography and ionhyphen;beam milling. As bias field is increased, at given current and pulse width, the velocity decreases, passes through a minimum, then increases again. The domain drag drive field at a given bias is derived both from the critical current at which motion begins and from the slope of velocity with current. A theory for the domain drag drive fieldHdof a bubble raft with infinite length along the current direction is derived, giving the simple resultHd/bgr;jD= 1/2(d0/D) minus;(pgr;/4sqrt;3)(d0/D)3, where bgr; is the Hall angle,jis the current density,d0is the bubble diameter, andDis the nearesthyphen;neighbor spacing. Experimental results from critical current agree approximately with the theory, but results from velocity slope with current are a factor of 3 too high.
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