Configuring a Bistable Atomic Switch by Repeated Electrochemical Cycling

Abstract

Recently, we have reported the stable and reproducible operation of atomic-scale switches, which allow us to open and close an electrical circuit by the controlled reconfiguration of silver atoms within an atomic-scale junction. Here, we investigate the operation of such atomic quantum switches, and we study in more detail the process during which these switches are formed by repeated electrochemical deposition and dissolution. We find that only after repeated deposition/dissolution cycles, a bistable contact is formed on the atomic scale, which allows to switch between a configuration where the contact is closed, the conducting state or “on”-state, and a configuration where the contact is open, the non-conducting state or “off”-state. We demonstrate that before a bistable contact is formed, irregular changes of the contact conductance are observed as a function of the electrochemical cycling process. A sudden transition to regular switching of the contact between a well-defined “on”-state and the non-conducting “off”-state is observed, which indicates the formation of a bistable contact configuration. Conductance quantization at integer multiples of the conductance quantum G₀ = 2e²/h (≈1/12.9 kΩ) is found at room temperature for the “on”- state conductance.