Common features of low-temperature spin–charge separation and superlattice formation in multiferroic manganites and antiferromagnetic cuprates

Abstract

The paper reports on new results obtained for tetragonal quasi-2D antiferromagnetic Eu2CuO4 at temperatures below 30–40 K. A set of ferromagnetic resonance lines similar to ones obtained earlier for a number of multiferroic manganites (Sanina et al 2012 J. Phys.: Condens. Matter 24 346002), with similar electric polarization and local conductivity, were measured, i.e., a multiferroic behavior was revealed in Eu2CuO4 at low temperatures. We attribute these observations to the 1D superlattices that are formed due to phase separation and self-organization of charge carriers and occupy a small crystal volume, as in the multiferroic manganites studied earlier. Characteristic features of these superlattices include a spin–charge separation and conductivity in their ferromagnetic layers. It is supposed that superlattices are domain walls separating the volume antiferromagnetic domains. A similarity between the superlattices in a number of crystals having different symmetries and bulk properties suggests that a topological order similar to that of the topological insulator exists in them at low temperatures.