  Effects of alloying on the electronic and magnetic properties of
Mn$_{x}$Co$_{y}$ ($x+y$=$n$=2-5; $x$=0-$n$) and Mn$_2$Co$_{11}$ nanoalloy
clusters are investigated using the density functional theory (DFT). Unlike the
bulk alloy, the Co-rich clusters are found to be ferromagnetic and the magnetic
moment increases with Mn-concentration, and is larger than the moment of pure
Co$_n$ clusters of same size. For a particular sized cluster the magnetic
moment increases by 2 $\mu_B$/Mn-substitution, which is found to be independent
of the size and composition. All these results are in good agreement with
recent Stern-Gerlach (SG) experiments [Phys. Rev. B {\bf 75}, 014401 (2007) and
Phys. Rev. Lett. {\bf 98}, 113401 (2007)]. Likewise in bulk Mn$_x$Co$_{1-x}$
alloy, the local Co-moment decreases with increasing Mn-concentration.

Atomic and Molecular Clusters;Computational Physics