  Current fluctuations can provide additional insight into quantum transport in
mesoscopic systems. The present work is carried out for the fluctuation
properties of transport through a pair of coupled quantum dots which are
connected with ferromagnetic electrodes. Based on an efficient
particle-number-resolved master equation approach, we are concerned with not
only fluctuations of the total charge and spin currents, but also of each
individual spin-dependent component. As a result of competition among the spin
polarization, Coulomb interaction, and dot-dot tunnel coupling, rich behaviors
are found for the self- and mutual-correlation functions of the spin-dependent
currents.
