Asymmetrization with electrical stimulus of the memristive response of symmetrical devices

S. BENGIÓ; J. LECOURT; C. FERREYRA; C.ACHA; U. LÜDERS; M. J. SÁNCHEZ; M. AGUIRRE; D. RUBI

Dresden

Congreso; MEMRISYS2019; 2019

MEMRISYS2019

Resistive RRAM memories are firm candidates to constitute the next generation of non-volatile memories. Their operation is based on the so-called resistive switching effect displayed by metal/oxide/metal systems able to reversible switch their electrical resistance between different non-volatile states. Resistive switching has been ubiquitously found in transition metal oxides, both binary (TaOx, TiOx, HfOx) and complex (cuprates, manganites). In many cases, the resistive change is mainly localized at oxide/metal interfaces and related to oxygen vacancies electromigration, for example, via modulation of interfacial Schottky barriers. Common wisdom says that in order to maximize the window between high and low resistance states -one of the fundamental figures that characterize the memory behavior- one must work with asymmetric devices, where one of the interfaces is ohmic and inactive and other one is active and concentrates the resistive change. Such asymmetry is usually achieved by using metals with different work functions for both electrodes. In this work we show that by appropriately tuning the electrical stimulus protocol in symmetrical Ag/La1/3Ca2/3MnO3/Ag and Pt/TaOx/Pt systems, it is possible to selectively activate or deactivate the resistive switching response of each interface, obtaining electrical responses similar to those found in asymmetric devices. By the adaptation of the VEOV model to both systems [1,2], we numerically reproduce the experimental measurements and get a deep insight into the involved oxygen vacancies dynamics.