Voltage- And Redox State-Triggered Oxygen Adatom Conductance Switch

Switches are omnipresent in all electronic devices. Miniaturization reduced the size of switches down to atomic dimensions. While on-surface tip-tuned molecular switches have recently been widely studied, atomic switches have received much less attention despite the fact that they could, in addition to the size, also reduce the switching times by orders of magnitude by tuning directly their electronic rather than atomic states. We have studied an ultrafast tip-tuned conductance switch which can switch reversibly and repeatedly by the applied bias. The switch is realized by an oxygen adatom supported on a rutile TiO₂surface whose redox state can be switched between −1, −2, and 0, the former being conducting and the latter two nonconducting. Advanced simulations suggest that for virtually identical current bias traces, several mechanisms, such as discharge/recharge via a state of a nearby polaron or via a highly energetically unfavorable neutral redox state, are involved.