A multiferroic molecular magnetic qubit.

The chiral FeO(NCH)(OCCH) molecular cation, with C symmetry, is composed of three six-fold coordinated spin-carrying Fe cations that form a perfect equilateral triangle. Experimental reports demonstrating the spin-electric effect in this system also identify the presence of a magnetic uniaxis and suggest that this molecule may be a good candidate for an externally controllable molecular qubit. Here, we demonstrate, using standard density-functional methods, that the spin-electric behavior of this molecule could be even more interesting as there are energetically competitive reference states associated with both high and low local spins (S = 5/2 vs S = 1/2) on the Fe ions. Each of these structures allow for spin-electric ground states. We find that qualitative differences in the broadening of the Fe(2s) and O(1s) core levels, shifts in the core-level energies, and the magnetic signatures of the single-spin anisotropy Hamiltonian may be used to confirm whether a transition between a high-spin manifold and a low spin manifold occurs.