Highly-symmetrized MnAu nanoalloys may possess high magnetic moments for potential application. The magnetic properties of MnAu nanoclusters exhibit strong dependence on the cluster sizes and morphologies. Determining the most stable morphologies as well as their spin-polarization patterns is important for their further application. Researchers at University of Nebraska MRSEC performed a joint theoretical/experimental study to investigate relative stabilities of various highly-symmetrized morphologies of MnAu clusters with different sizes (ACS NANO 5, 9966 9 (2011)). Based on an extensive search, they found that the antiferromagnetic spin configurations are the most stable for all the morphologies investigated. As the size increases, the most stable morphology of MnAu nanocluster evolves from a core-shell structure to L10 structure, and starting from 1.7 nm size the L10 structures become more stable, confirmed by the high-resolution transmission electron microscopy experiment. Both the antiferromagnetic and ferromagnetic states for the L10 MnAu nanoclusters larger than 2 nm are likely to be energetically stable at room temperature. Because their closeness in cohesive energies, there is possible existence of both antiferromagnetic and ferromagnetic states for L10 MnAu nanoclusters in different sizes, and this mixed system can be useful for applications such as exchange bias.
