Out-of-plane Enhanced Magnetic Anisotropy Energy in Nickel-Benzene Complexes

Organometallic complexes formed by transition metals clusters and benzene molecules have already been synthesized, and in selected cases display magnetic properties controlled by external magnetic fields. We herein investigate NinBzn complexes made of nickel atoms surrounded by benzene molecules and focus specifically on magnetic Ni3Bz3 molecule. By means of calculations including relativistic spin-orbit terms, we show that this molecule reveals a large magnetic anisotropy energy of approximately 8 meV, found with the easy axis out-of-plane to the metal atoms. Note that the matching bare Ni3 cluster have a large magnetic anisotropy and the easy axis is in-plane. Benzene molecules are thus switching the easy axis from in-plane for Ni3 to out-of-plane for Ni3Bz3 when covered with benzene molecules. The large out-of-plane magnetic anisotropy of Ni3Bz3 suggests that this molecule could indeed be used as part in the design of molecular magnetic memories.