Electronic Structure and Transport Through Single Molecule Magnets

Over the past decade, single-molecule magnets have drawn considerable attention due to observed magnetic quantum tunneling and interference and a possibility of using them for information storage or devices. There have been so far significant experimental efforts to build and characterize monolayers of single-molecule magnets on various surfaces or single-molecule magnets connected to electrodes. There is need to understand changes of electronic and magnetic properties of single-molecule magnets in those environments using quantum mechanical simulations. We simulate, within density-functional theory, a nanostructure in which prototype single-molecule magnets Mn12 are adsorbed onto a gold surface. We investigate coupling between the Mn12 and the surface and discuss electronic structure and magnetic anisotropy of the Mn12 on a gold surface in comparison to an isolated Mn12. In addition, we present electron transport properties through a Mn12 bridged between gold electrodes, using the nonequilibrium Green's function method in conjunction with density-functional theory. We discuss a possibility of using a Mn12 molecule as a spin filter and an effect of interface geometry and bonding type on transport across a Mn12.