Force-based reading and writing of individual single-atom magnets.

The integration of single-atom bits enables the realization of the highest data-density memory. Reading and writing information to these bits through mechanical interactions opens the possibility of operating the magnetic devices with low heat generation and high density recording. To achieve this visionary goal, we demonstrate the use of magnetic exchange force microscopy to read and write the spin orientation of individual holmium adatoms on MgO thin films. The spin orientation of the holmium adatom is stabilized by the strong uniaxial anisotropy of the adsorption site and can be read out by measuring the exchange forces between the magnetic tip and the atom. The spin orientation can be written by approaching the tip closer to the holmium adatom. We explain this writing mechanism by the symmetry reduction of the adsorption site of the Ho adatom. These findings demonstrate the potential for information storage with minimal energy loss and pave the way for a new field of atomic-scale mechano-spintronics.