Electric field tuning of magnetic states in single magnetic molecules
Yan Lü, Yunlong Wang, Linghan Zhu, Li Yang, Li Wang
Abstract
Single magnetic molecules may be the smallest functional magnets. An electric-field controllable spin state of magnetic molecules is of fundamental importance for applications while its realization remains challenging. To date the observed spin-electric interaction based on spin-orbit coupling or spin dipole coupling is useful to tune fine spin structures but too weak to flip the spin state. In this work, we propose a mechanism to realize enhanced spin-electric coupling and flip the spin states by tuning the spin superexchange between local spins. Using first-principles calculations and the Heisenberg Hamiltonian, we demonstrate this effect in a family of magnetic molecules, transition metallic porphyrins. We show that their $d\text{\ensuremath{-}}\ensuremath{\pi}$ and $\ensuremath{\pi}\text{\ensuremath{-}}\ensuremath{\pi}$ spin superexchange couplings are determined by the relative energies of $d$ and $\ensuremath{\pi}$ electronic states, which are sensitive to the applied electric field. Therefore, applying electric field can tune a wide range of magnetic ground states, including ferromagnetic, ferrimagnetic, and antiferromagnetic configurations. This spin-electric coupling may provide a different approach for designing and controlling molecular spintronics.