Magnetic resonance imaging of single atoms on a surface

Magnetic resonance imaging (MRI) revolutionized diagnostic medicine and biomedical research by allowing non-invasive access to spin ensembles 1 . To enhance MRI resolution to the nanometre scale, new approaches 2 – 4 including scanning probe methods 5 – 8 have been used in recent years, which culminated in the detection of individual spins 5 , 6 . This allowed for the visualization of organic samples 9 and magnetic structures 10 , 11 , as well as identifying the location of electron 7 , 8 and nuclear spins 12 . Here, we demonstrate the MRI of individual atoms on a surface. The set-up, implemented in a cryogenic scanning tunnelling microscope, uses single-atom electron spin resonance 13 , 14 to achieve subångström resolution, exceeding the spatial resolution of previous MRI experiments 5 – 8 by one to two orders of magnitude. We find that MRI scans of different atomic species and with different probe tips lead to unique signatures in the resonance images. These signatures reveal the magnetic interactions between the tip and the atom, in particular magnetic dipolar and exchange interaction.