Magnetic and magnetoelectric properties of Ho2BaNiO5

The compounds R2BaNiO5, with R a rare earth, exhibit low dimensional magnetism including a Haldane gap, originating from Ni2+ chains. In these compounds, the rare-earth ions give rise to three-dimensional antiferromagnetic ordering which does not eliminate the Haldane-like behavior. We study here the interplay between magnetic and dielectric properties of Ho2BaNiO5 on a polycrystalline sample. We show that a linear magnetoelectric effect exists in this compound. We discuss our results in the light of the rich magnetic phase diagram of Ho2BaNiO5.