Canted antiferromagnet superimposed on a buckled kagomé network in RbMn4(PO4)3

Abstract

Rubidium tetramanganese tris(phosphate), RbMn4(PO4)3, has been synthesized as single crystals under hydrothermal conditions. The crystal structure was refined in the space groupPnnm(D2h12). It is argued that the size factorRM/RA,i.e.the ratio of theA+ionic radius to theM2+ionic radius, within the morphotropic seriesAM4(TO4)3corresponds to a specific type of crystal structure. At low temperatures, the antiferromagnet superimposed on a buckled kagomé network in RbMn4(PO4)3experiences a transition into a long-range ordered state with finite spontaneous magnetization. First principles calculations provide the dominant magnetic exchange interactions both within and between the kagomé layers. The analysis of these interactions allows us to suggest a model of alternating ferromagnetic and antiferromagnetic arrangements within chains of Mn3 atoms.