Stripe-domain dynamics in bubble-domain circuits

It is widely known that bubble domains can exist when the bias field is between the elliptic instability (runout) field Heand the bubble collapse field Hbc. Values for Heand Hbcwere calculated by Thiele. It is not widely recognized that long stripe domains can also exist in the bottom 20% of this range. Stripes are stable up to the "stripe contraction" field, Hsc, which is about 0.02 M/μ0above Hefor thickness over intrinsic length, , values from 4 to 10. (Hbcis about 0.10 M/μ0above He.) Values for Hscwere calculated by Kooy and Enz of Philips Research Labs. in 1960, although the importance of their result to bubble-domain devices was not apparent at the time. The velocity of the domain tip during stripout and contraction such as occurs during domain detection or transfer is important for calculating maximum circuit speeds. This is given by , where is the field (bias field plus local field from currents or Permalloy elements), is the wall mobility, and is a constant approximately equal to 0.5.