  In this paper, we have focused on a comparison of the different magnetic
properties of the three nano-Heusler Ru$_2$Mn$_X$ (X = Nb, Ta or V) compounds
using the Blume-Capel Ising model. The Heusler structures are composed by
different mixed spins. In fact, the Ru and Mn atoms are modeled by spin-5/2 and
spin-1/2, respectively. While, the X atoms ($X$ = Nb, Ta and V) are represented
by the spin-7/2, spin-3/2 and spin-5/2, respectively. This study is carried out
by using the Monte Carlo simulations under the Metropolis algorithm. The
magnetic behaviors of the three nano-Heusler compounds have been studied and
discussed. It is found that Ferrimagnetic to superparamagnetic transitions were
observed corresponding to different blocking temperatures. Besides, the effect
of the crystal field, the exchange coupling interactions and the external
magnetic field have been inspected on the magnetization of each nano-Heusler
compound Ru$_2$Mn$_X$ ($X$ = Nb, Ta or V).
