When electrons tunnel through an atom, they may lose energy in the process. Such inelastic cotunneling events render the atom in an excited state, either with a flipped spin or with an entirely different orbital filling. In our recent paper in Nano Letters by Ben Bryant et al., we report the observation of both types of cotunneling events. In addition, we demonstrate how both inelastic cotunneling processes may be switched off entirely through a controlled modification of the immediate environment of the atom. This work provides starting points for research on engineering the slowdown of decoherence in atomic spin systems.
Tunneling spectroscopy measurements performed on individual cobalt atoms assembled into a chain. Inelastic cotunneling events are observed as steps in the spectroscopy. For atoms in the inside of the chain, complete suppression of these steps is observed.