Ferroelectric Control Of Single-molecule Magnetism In 2D Limit:A First Principles Study

The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of low-power consumption and high-density storage devices.The manipulation of magnetic states via the strain effect or the external electric field is based on volatile control,i.e.,the magnetic states will switch back to the original ones if the electric field is removed.In comparison,ferroelectric materials with reversible spontaneous electric polarization under external electric field provide promising platform for nonvolatile manipulation.However,a general problem for the conventional ferroelectric materials is the possible critical thickness effect,since their ferroelectric performance is deteriorated with the reduced size which limits their applications in nanoelectronics.Recent breakthrough in successful synthesis of two-dimensional?2D?ferroelectric materials in experiment opens up new opportunities for nonvolatile manipulation at the molecular scale.Based on first-principles calculations,a magnetoelectric effect is proposed to effectively tune the molecular magnetization by the reversal of the 2D ferroelectric substrate.The results show that the magnetic states of metal-phthalocyanine molecules?MPc?can be switched between nonzero and zero,and the easy axes can be switched between in-plane and out-of-plane by reversing the electric polarization of the underlying 2D?-In₂Se₃ substrate.Moreover,the magnetic moments and magnetic anisotropy energies?MAE?of the system can be further largely enhanced by a functionalized halogen atom atop the MPc molecule.The I-OsPc/In₂Se₃ system possesses large MAE up to 30 meV at both polarization directions,which is sufficient for room-temperature applications.The underlying mechanism of the switchable magnetic states was further revealed by the energy diagrams and the matrix elements of the SOC Hamiltonian.Detailed analysis proves that the different electric polarization of?-In₂Se₃ alters the hybridization between the molecule and substrate,and the occupation of electrons on the hybrid states further influences the magnetic properties.These findings provide a feasible scheme to realize ferroelectric control of magnetic states in 2D limit.