Exotic spin structures in nanoscale coordination clusters incorporating 4f ions

Coordination clusters containing 4f metal ions can show a number of remarkable magnetic behaviors beyond that of acting as Single Molecule Magnets (SMMs). This is a consequence of strong spin-orbit coupling effects which lead to unusually anisotropic spins for many of the 4f electron configurations. The dysprosium³⁺ ion is the most famous example of an ion with an oblate anisotropy ellipsoid and this leads to an Ising spin ground state, i.e. with the spin oriented along the z-axis and with tiny spin components in the xy plane. This, in turn, can lead to exotic spin systems such as the first identified molecular realization of a toroidal spin system in a molecule containing a Dy₃ triangle which was produced and studied in our laboratory and became a molecule of interest with our longstanding collaborators [1-3] 

Further such toroidal Dy₃ triangles will be presented, including ones where the triangular arrangement is supported and/or induced by the presence of 3d transition metal ions. 

In addition, two cyclic Fe^III -Dy^III systems will be described where a solenoidal toroidal moment can be disrupted into what is possibly a molecular realization of an anyon-based [4] arrangement of spin partners.

Description

Toroidal moments are most easily understood for triangular systems where the spin vectors lie in plane (or plate for the 3 hares sharing 3 ears motif).

[1] J. Tang, I. Hewitt, N. T. Madhu, G. Chastanet, W. Wernsdorfer, C. E. Anson, C. Benelli, R. Sessoli, A. K. Powell, Angew. Chem. Int. Ed., 2006, 45, 1729. 

[2] L. Chibotaru, A. Soncini, Angew. Chem Int. Ed., 2008, 45, 4126. 

[3] J. Luzon, K. Bernot, I. J. Hewitt, C. E. Anson, A. K. Powell, R. Sessoli, Phys. Rev. Lett., 2008, 100, 247205. 

[4] D. Castelvecchi, Nature, 2020, 583, 176.