Magnetism in small bimetallic Mn-Co clusters

TL;DR

This study uses density functional theory to explore how alloying affects the electronic and magnetic properties of small Mn-Co clusters, revealing ferromagnetism in Co-rich clusters and a consistent increase in magnetic moments with Mn substitution.

Contribution

It provides the first detailed DFT analysis of magnetic properties in small Mn-Co nanoalloy clusters, aligning with recent experimental findings.

Findings

Co-rich clusters are ferromagnetic.

Magnetic moment increases with Mn concentration.

Results agree with recent Stern-Gerlach experiments.

Abstract

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.