title: Manipulating magnetism of MnO nano-clusters by tuning the stoichiometry and charge state.
abstract: In this paper, we have studied the composition dependent evolution of geometric and magnetic structures of MnO clusters within density functional theory. The magnetic structures are determined by the competition between direct and superexchange interactions, which have been analyzed by the parameters obtained from maximally localized Wannier functions. The intrinsic electronic structures of the clusters have been thoroughly studied by looking into the hybridization (quantified using the Hybridization Index) and charge transfer scenario. Further, the importance of electron correlation in describing simple Mn-dimer and MnO clusters has been discussed within the Hubbard model and hybrid exchange-correlation functional. Our calculated vertical detachment energies of off-stoichiometric MnO clusters compare well with the recent experimental results. Interestingly, the charged state of the cluster strongly influences the geometry and the magnetic structure of the cluster, which are very different from the corresponding neutral counterpart. We have demonstrated that the exchange interaction between Mn atoms can be switched between ferromagnetic and anitiferromagnetic ones by changing the charge state and hence can be useful for spin-based information technology.
authors.affiliation: Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden.
authors.forename: Shreemoyee
authors.initials: S
authors.lastname: Ganguly
authors.forename: Mukul
authors.initials: M
authors.lastname: Kabir
authors.forename: Carmine
authors.initials: C
authors.lastname: Autieri
authors.forename: Biplab
authors.initials: B
authors.lastname: Sanyal