Controlled Complete Suppression of Single-Atom Inelastic Spin and Orbital Cotunneling

The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom’s spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here, we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom’s environment, using scanning tunneling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chains on a Cu2N substrate, indicates a structural transition affecting the dz2 orbital, effectively cutting off the STM tip from the spin-flip cotunneling path.

This work was supported by the Dutch funding organizations FOM and NWO (VIDI) and by the Kavli Foundation. J.F.R. acknowledges financial support by MEC-Spain (FIS2013-47328-C2-2-P) and Generalitat Valenciana (ACOMP/2010/070 and Prometeo). This work has been financially supported in part by FEDER funds. J.L.L. and J.F.R. acknowledge financial support by Marie-Curie-ITN 607904-SPINOGRAPH. A.F. acknowledges Marie Curie COFUND (Grant 600375) and CONICET.