  Different models have been used to evaluate the interfacial
Dzyaloshinskii-Moriya interaction (DMI) from the asymmetric bubble expansion
method using magneto-optics. Here we investigate the most promising candidates
over a range of different magnetic multilayers with perpendicular anisotropy.
Models based on the standard creep hypothesis are not able to reproduce the
domain wall (DW) velocity profile when the DW roughness is high. Our results
demonstrate that the DW roughness and the interface roughness of the sample
layers are correlated. Furthermore, we give guidance on how to obtain reliable
results for the DMI value with this popular method. A comparison of the results
with Brillouin light scattering (BLS) measurements on the same samples shows
that the BLS approach often results in higher measured values of DMI.
