  Theoretical studies dealing with current-driven domain wall dynamics in
ferrimagnetic alloys and, by extension, other antiferromagnetically coupled
systems as some multilayers, are here presented. The analysis has been made by
means of micromagnetic simulations that consider these systems as constituted
by two subsystems coupled in terms of an additional exchange interlacing them.
Both subsystems differ in their respective gyromagnetic ratios and temperature
dependence. Other interactions, as for example anisotropic exchange or
spin-orbit torques, can be accounted for differently within each subsystem
according to the physical structure. Micromagnetic simulations are also
endorsed by means of a collective coordinates model which, in contrast with
some previous approaches to these antiferromagnetically coupled systems, based
on effective parameters, also considers them as formed by two coupled
subsystems with experimentally definite parameters. Both simulations and the
collective model reinforce the angular moment compensation argument as
accountable for the linear increase with current of domain wall velocities in
these alloys at a certain temperature or composition. Importantly, the proposed
approach by means of two coupled subsystems permits to infer relevant results
in the development of future experimental setups that are unattainable by means
of effective models.
