Cluster Magnetism of Ba 4 NbMn 3 O 12 : Localized Electrons or Molecular Orbitals?

Abstract

Recently synthesized Ba 4 NbMn 3 O 12 belong to cluster magnets that are systems with tightly bound groups of magnetic ions, in this case Mn 3 trimers. Such magnetic clusters can often be described by molecular orbitals, however strong electron correlations may invalidate this description. To understand the electronic and magnetic state of Ba 4 NbMn 3 O 12 we carried out ab initio calculations and show that this system is better described not in molecular orbitals picture, but as a system with electrons localized on the Mn ions, with strong intracluster and weaker inter-cluster exchange. The calculated spin of the Mn 3 trimer is S = 2, in agreement with the experiment. The predicted magnetic structure of Ba 4 NbMn 3 O 12 is that of ferromagnetic layers of Mn 3 trimers, stacked antiferromagnetically. © 2018, Pleiades Publishing, Inc.