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We theoretically investigate a family of spin-frustrated triangular molecular nanomagnets with arbitrary on-site spin, featuring one heterometallic ion, in the limit of zero spin-orbit coupling. Analytical evaluation of the Heisenberg exchange states and spectrum shows that the ground state can either be the first example of a toroidal quartet, or feature two weakly split toroidal doublets, depending on the exchange parameters. The nonequilibrium spin dynamics of these toroidal states is modelled within a three-terminal molecular spintronics device, showing that gate and bias voltages can be used to tune the nonequilibrium population of these toroidal states, thus to monitor the ensuing toroidal magnetization of the device.

We present the syntheses, structures, magnetic data and theoretical analyses for two families of heptanuclear clusters, wherein two staggered dysprosium(III) triangles are linked by various M(III) d-/p-block ions. The families differ in the counter-anion and are of formulae [DyIII6MIII(OH)8(o-tol)12(MeOH)5(NO3)] ⋅ 4MeOH and [DyIII6MIII(OH)8(o-tol)12(MeOH)6]Cl ⋅ 6MeOH (M=Cr, Mn, Fe, Co, Al; o-tol=o-toluate). We find that variation of the central metal ion M is crucial in tuning the toroidal moments on the triangular units, with diamagnetic M linking ions enhancing the ferrotoroidic coupling. By detailed simulation and analysis of various magnetic measurements, including sub-kelvin microSquid hysteresis loops, we identified the specific signature of the M linking ions’ modulation of toroidal properties, including the mechanism whereby anisotropic, paramagnetic M ions lead to hysteresis profiles with larger remnant magnetisations and broader coercive fields.