Topological effects on the magnetic properties of closed and open ring-shaped Cr-based antiferromagnetic nanomagnets

Topological effects on magnetic properties were revealed by an experimental and theoretical investigation on two Cr-based ring-shaped nanomagnets Cr8 and Cr8Cd as model systems for ``closed'' and ``open'' antiferromagnetic rings, respectively. The detailed structures of the low-lying energy levels in terms of the total spin were established directly by high-field magnetization measurements up to 57 T. All the differences observed in the magnetization curve of the two systems can be interpreted by the different topology of the magnetic coupling scheme whereby the experimental observations are well reproduced by theoretical calculations.