Large magnetic anisotropy in chemically engineered iridium dimer

Abstract Exploring giant magnetic anisotropy in small magnetic nanostructures is of technological merit for information storage. Large magnetic anisotropy energy (MAE) over 50 meV in magnetic nanostructure is desired for practical applications. Here we show the possibility to boost the magnetic anisotropy of the smallest magnetic nanostructure—transition metal dimer. Through systematic first-principles calculations, we proposed an effective way to enhance the MAE of an iridium dimer from 77 meV to 223–294 meV by simply attaching a halogen atom at one end of the Ir–Ir bond. The underlying mechanism for the enormous MAE is attributed to the rearrangement of the molecular orbitals which alters the spin-orbit coupling Hamiltonian and hence the magnetic anisotropy. Our strategy can be generalized to design other magnetic molecules or clusters to obtain giant magnetic anisotropy.