Homochiral toroidal spin state in Dy(III)-based single-molecule toroics

Single-molecule toroics, materials that combine spin and chirality at the molecular level, are promising candidates for applications in data storage, chiral spintronics and magnetoelectric devices. Over the past two decades, substantial progress has been made in the design of toroidal spin states via ligand design and coordination chemistry strategies. However, achieving homochiral magnetic vortex configurations across both molecular and unit-cell scales—a key prerequisite to induce the toroidal polarization using a homogeneous magnetic field—remains challenging. Here we report enantiopure chiral dysprosium triangles in which introduction of structural chirality induces spin homochirality. µ-SQUID magnetometry and ab initio calculations evidence a non-coplanar spin texture that exhibits a toroidal ground state at low temperature. Furthermore, magneto-chiral dichroism spectroscopy, a technique sensitive to both chirality and magnetization, reveals unusual behaviours below 4.5 K, the temperature at which the coupling between Dy(III) ions favours the generation of a toroidal spin state.