Toroidal spin states in molecular magnets
Y. Pavlyukh
Abstract
Toroidal spin arrangements are emerging as promising candidates for the realization of quantum state manipulation in single molecule magnets (SMM). Being protected by weak short-range interactions, they are formed spontaneously due to simultaneous time- and space-inversion symmetry breaking. While according to the Mermin-Wagner theorem, the toroidal moment vanishes in the thermodynamic limit, the toroidal ground states could still exist in finite spin systems, remarkably, in magnetic trimers as our exact diagonalization reveals. Here we demonstrate a mechanism with which toroidal states can be induced and controlled externally using an electric field by the interplay of the spin-orbit coupling and the Aharonov-Casher effect. Conditions for the observation using the Landau-Zener-St\"uckelberg interferometry are identified. A control of symmetry-broken toroidal magnetic states in spin rings with Heisenberg exchange interactions is demonstrated as a paradigm for the quantum state manipulation.