Magnetic exchange force microscopy with atomic resolution

The miniaturization of electronic, spintronic and other devices means that magnetic active elements are reaching nanometre dimensions, where the magnetic properties of individual atoms become increasingly important. Until recently the only way of imaging atomic magnetic moments (or spins) was spin polarized scanning tunnelling microscopy, which can achieve atomic resolution but only on conducting surfaces. Magnetic exchange force microscopy (MExFM), essentially the use of an atomic force microscope with a magnetic tip to sense the magnetic exchange force between the spin of atoms at the tip and a sample surface, was proposed to overcome this limitation. Theory predicts the feasibility of MExFM, and now a group at the University of Hamburg reports the first successful use of the technique, using a ferromagnetic tip to reveal the arrangement of both surface atoms and their spin on the antiferromagnetic insulator nickel oxide.