  We analyse the impact of growth conditions on asymmetric magnetic bubble
expansion under in-plane field in ultrathin Pt / Co / Pt films. Specifically,
using sputter deposition we vary the Ar pressure during the growth of the top
Pt layer. This induces a large change in the interfacial structure as evidenced
by a factor three change in the effective perpendicular magnetic anisotropy.
Strikingly, a discrepancy between the current theory for domain-wall
propagation based on a simple domain-wall energy density and our experimental
results is found. This calls for further theoretical development of domain-wall
creep under in-plane fields and varying structural asymmetry.
