  We study the spin-resolved subgap transport in a triple quantum-dot system
coupled to one superconducting and two ferromagnetic leads. We examine the
Andreev processes in the parallel and antiparallel alignments of ferromagnets
magnetic moments in both the linear and nonlinear response regimes. The
emphasis is put on the analysis of the current cross-correlations between the
currents flowing through the left and right arms of the device and relevant
electron waiting time distributions. We show that both quantities can give an
important insight into the subgap transport processes and their analysis can
help optimizing the system parameters for achieving the considerable Andreev
current and efficient Cooper pair splitting. Strong positive values of
cross-correlations are associated with the presence of tunneling processes
enhancing the Cooper pair splitting efficiency, while short waiting times for
electrons tunneling through distinct ferromagnetic contacts indicate fast
splitting of emitted Cooper pairs. In particular, we study two detuning schemes
and show that antisymmetric shift of side quantum dots energy levels is
favorable for efficient Cooper pair splitting. The analysis of spin-resolved
waiting time distributions supports the performance enhancement due to the
presence of ferromagnetic contacts, which is in particular revealed for short
times. Finally, we consider the effect of changing the inter-dot hopping
amplitude and predict that strong inter-dot correlations lead to a reduction of
Andreev transport properties in low-bias limit.
