Large perpendicular magnetic anisotropy of transition metal dimers driven by polarization switching of a two-dimensional ferroelectric In 2 Se 3 substrate

Large perpendicular magnetic anisotropy (MA) is highly desirable for realizing atomic-scale magnetic data storage which represents the ultimate limit of the density of magnetic recording. In this work, we study the MA of transition metal dimers Co–Os, Co–Co and Os–Os adsorbed on two-dimensional ferroelectric In 2 Se 3 (In 2 Se 3 -CoOs, In 2 Se 3 -OsCo, In 2 Se 3 -CoCo and In 2 Se 3 -OsOs) using first-principles calculations. We find that the Co–Os dimer in In 2 Se 3 -CoOs has a total magnetic anisotropy energy (MAE) of ∼40 meV. The MAE arising from the Os atom in In 2 Se 3 -CoOs is up to ∼60 meV. Such large MAE is attributed to the high spin–orbit coupling constant and the onefold coordination of the Os atom. In addition, perpendicular MA can be enhanced in In 2 Se 3 -CoOs and induced in In 2 Se 3 -OsCo, In 2 Se 3 -CoCo and In 2 Se 3 -OsOs by the ferroelectric polarization reversal of In 2 Se 3 . We demonstrate that the enlargement of exchange splitting of d xy /d x 2 − y 2 and d xz /d yz orbitals for Os atoms in In 2 Se 3 -OsOs, Co atom in In 2 Se 3 -CoOs and Os and Co atoms in In 2 Se 3 -OsCo is responsible for the increase of MAE; while, for the upper Co atom in In 2 Se 3 -CoCo and the Os atom in In 2 Se 3 -CoOs, the energy rise of the d z 2 orbital owing to the change of the crystal field effect by the reversal of ferroelectric polarization results in the increase of MAE.