The first paper of the Otte Lab has appeared in Physical Review Letters:
Local Control of Single Atom Magnetocrystalline Anisotropy
When a magnetic atom is embedded in a material, magnetocrystalline anisotropy causes its magnetic moment to favor certain axes over others to orient itself along. It is this property that ultimately makes a material magnetically stable. Delft researchers Ben Bryant and Anna Spinelli, both working in the Otte Lab, have now demonstrated that this magnetic anisotropy can be tuned with local atomic precision.
The experiments were performed by positioning individual iron atoms close to each other onto a surface by means of a low-temperature scanning tunneling microscope. Inelastic electron tunneling spectroscopy was used to probe the quantum spin states of the atoms. By adjusting the relative orientation of two atoms, shifts in the excitation energies were observed resulting from changes in the magnetic anisotropy. Through careful investigation of the direct crystalline environment of the atoms these changes can be understood in terms of variations of the bond angles between the iron atoms and their neighbors.
STM images of different atomic geometries studied. For the linear relative orientation in the left image the magnetic anisotropy of the atoms was found to be enhanced whereas for the diagonal orientation on the right it was reduced.