We introduce a model that accounts for the bipolar resistive switching phenomenom observed in transition metal oxides. It qualitatively describes the electric field-enhanced migration of oxygen vacancies at the nano-scale. The numerical study of the model predicts that strong electric fields develop in the highly resistive dielectric-electrode interfaces, leading to a spatially inhomogeneous oxygen vacancies distribution and a concomitant resistive switching effect. The theoretical results qualitatively reproduce non-trivial resistance hysteresis experiments that we also report, providing key validation to our model.

Progress of silicon-based technology is nearing its physical limit, as the minimum feature size of components is reaching a mere 10 nm. The resistive switching behavior of transition metal oxides and the associated memristor device is emerging as a competitive technology for next-generation electronics. Significant progress has already been made in the past decade, and devices are beginning to hit the market; however, this progress has mainly been the result of empirical trial and error. Hence, gaining theoretical insight is of the essence. In the present work, we report the striking result of a connection between the resistive switching and shock-wave formation, a classic topic of nonlinear dynamics. We argue that the profile of oxygen vacancies that migrate during the commutation forms a shock wave that propagates through a highly resistive region of the device. We validate the scenario by means of model simulations and experiments in a manganese-oxide-based memristor device, and we extend our theory to the case of binary oxides. The shock-wave scenario brings unprecedented physical insight and enables us to rationalize the process of oxygen-vacancy-driven resistive change with direct implications for a key technological aspect-the commutation speed. DOI: 10.1103/PhysRevX.6.011028 Subject Areas: Condensed Matter Physics, Materials Science, Nonlinear DynamicsThe information age we live in is made possible by a physical underlayer of electronic hardware, which originates in condensed-matter physics research. Despite the great progress made in recent decades, the demand for faster and power-efficient devices continues to grow. Thus, there is urgent need to identify novel materials and physical mechanisms for future electronic-device applications. In this context, transition metal oxides (TMOs) are attracting much attention for nonvolatile memory applications [1]. In particular, TMO are associated with the phenomenon of resistive switching (RS) [2] and the memristor device [3], which is emerging as a competitive technology for nextgeneration electronics [1,[4][5][6][7][8][9][10]. The RS effect is a large, rapid, nonvolatile, reversible change of the resistance, which may be used to encode logic information. In the simplest case, one may associate high and low resistance values to binary states, but multibit memory cells are also possible [11,12].Typical systems where RS is observed are two-terminal capacitor-like devices, where the dielectric might be a TMO and the electrodes are ordinary metals. The phenomenon occurs in a strikingly large variety of systemsranging from simple binary compounds, such as NiO, TiO 2 , ZnO, Ta 2 O 5 , HfO 2 , and CuO, to more complex perovskite structures, such as superconducting cuprates and colossal magnetoresistive manganites [2,4,6,9,13].From a conceptual point of view, the main challenges for a nonvolatile memory are as follows: (i) to change its resistance within nano seconds (required for modern electronics applications), (ii) to be able to retain the state for years (i.e., n...

Bipolar resistive switching in low cost n-Si/La2/3Ca1/3MnO3/M (M = Ti + Cu) devices was investigated. For low SET compliance currents (CC), an interfacial-related resistive switching mechanism, associated to the migration of oxygen vacancies close to the manganite/metal interface, is operative. Simulations using the voltage enhanced oxygen vacancies drift model validate our experimental results. When further increasing the CC, we have observed the onset of a second, filamentary, resistive switching regime with a concomitant collapse of the ON/OFF ratio. We finally demonstrate that it is possible to delay the onset of the filamentary regime by controlling the film thickness.

Articles you may be interested inElectric-pulse-induced resistance switching effect in the bulk of La0.5Ca0.5MnO3 ceramics AIP Advances 4, 047123 (2014) Multilevel resistance states in silver-manganite interfaces are studied both experimentally and through a realistic model that includes as a main ingredient the oxygen vacancies diffusion under applied electric fields. The switching threshold and amplitude studied through hysteresis switching loops are found to depend critically on the initial state. The associated vacancy profiles further unveil the prominent role of the effective electric field acting at the interfaces. While experimental results validate main assumptions of the model, the simulations allow to disentangle the microscopic mechanisms behind the resistive switching in metal-transition metal oxide interfaces.

We study the resistive switching (RS) mechanism as way to obtain multi-level memory cell (MLC) devices. In a MLC more than one bit of information can be stored in each cell. Here we identify one of the main conceptual difficulties that prevented the implementation of RS-based MLCs. We present a method to overcome these difficulties and to implement a 6-bit MLC device with a manganite-based RS device. This is done by precisely setting the remnant resistance of the RS-device to an arbitrary value. Our MLC system demonstrates that transition metal oxide non-volatile memories may compete with the currently available MLCs.