  The concept of non-Markovianity in open quantum systems is traditionally
associated with the existence of information backflows from the environment to
the system. Meanwhile, the mechanisms through which such backflows emerge are
still a subject of debate. In this work, we use collision models to study
memory effects in the dynamics of a qubit system in contact with a thermal bath
made up of few ancillas, in which system-ancilla and ancilla-ancilla
interactions are considered. In the single-ancilla limit case, we show that the
system-bath information flow exhibits an interesting mixture of chaotic and
regular oscillatory behavior, which depends on the interaction probabilities.
In parallel, our results clearly indicate that the information backflows
decrease when new ancillas are added to the bath, which sheds light on the
nature of the Markovian to non-Markovian transition.
