Dimensional crossover in magnetic warwickites

We present an investigation of the magnetic properties of a series of warwickites with different transition metals. These materials are characterized by one-dimensional structures called ribbons where the transition metals are randomly located. The present results allow for a systematic investigation of the hierarchy of magnetic interactions in these systems. While the intraribbon interactions are mainly direct $d$-$d$ interactions between the transition-metal ions, the interribbon interaction is due to superexchange between metals in different octahedra mediated by the oxygen in the common corner.