Experimental determination of single molecule toroic behaviour in a Dy8 single molecule magnet

Abstract

The enhancement of toroic motifs through coupling toroidal moments within molecular nanomagnets is a new, interesting and relevant approach for both fundamental research and potential quantum computation applications. We investigate a Dy₈ molecular cluster and discover it has a antiferrotoroic ground state with slow magnetic relaxation. The experimental characterization of the magnetic anisotropy axes of each magnetic center and their exchange interactions represents a considerable challenge due to the non-magnetic nature of the toroidal motif. To overcome this and obtain access to the low energy states of Dy₈ we establish a multi-orientation single-crystal micro Hall sensor magnetometry approach. Using an effective Hamiltonian model we then unpick the microscopic spin structure of Dy₈, leading to a canted antiferrotoroidic tetramer molecular ground state. These findings are supported with electrostatic calculations that independently confirm the experimentally determined magnetic anisotropy axes for each Dy^III ion within the molecule.