Oxygen vacancies dynamics in redox-based interfaces: Tailoring the memristive response

Abstract

Redox-based memristive devices are among the alternatives for the next generation of non volatile memories, but also candidates to emulate the behavior of synapses in neuromorphic computing devices. It is nowadays well established that the motion of oxygen vacancies (OV) at the nanoscale is the key mechanism to reversibly switch metal/insulator/metal structures from insulating to conducting, i.e. to accomplish the resistive switching effect. The control of OV dynamics has a direct effect on the resistance changes, and therefore on different figures of memristive devices, such as switching speed, retention, endurance or energy consumption. Advances in this direction demand not only experimental techniques that allow for measurements of OV dynamics, but also of theoretical studies that shed light on the involved mechanisms. Along this goal, we analize the OV dynamics in redox interfaces formed when an oxidizable metallic electrode is in contact with the insulating oxide. We show how the transfer of OV can be manipulated by using different electrical stimuli protocols to optimize device figures such as the ON/OFF ratio or the energy dissipation linked to the writing process. Analytical expressions for attained resistance values, including the high and low resistance states are derived in terms of total transferred OV in a nanoscale region of the interface. Our predictions are validated with experiments performed in Ti/La$_{1/3}$Ca$_{2/3}$MnO$_{3}$ redox memristive devices.