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of Moore's law in mind, industry and academia moved the focus to new approaches and alternative materials. In this scenario, resistive random access memories (RRAM) are considered promising candidates for the next generation of nonvolatile memories, due to their fast writing speed, high storage density, high endurance, long retention times, and low energy consumption. [1] By applying an electric stimulus, these devices exhibit a reversible change of resistance retained under zero-field conditions, and hence high and low resistance states (HRS and LRS, respectively) can be defined. In recent years, a great effort has been carried out to explain the origin of the effective change in resistance, and a wide range of possible mechanisms have been reported in the literature. [1,2] Some of the switching mechanisms rely on purely electronic effects, such as charge-trapping at an interface, modification of a Schottky barrier, or changes induced by electronic charge in strongly correlated electron systems of oxides, which can lead to metal-insulator transitions (MIT). On the other hand, ionic transport (drift) has also been reported as a mechanism able to induce a change of resistance in memristive devices. In electrochemical metallization memories, cations from an active electrode migrate reversibly in an insulating matrix, reaching the inert electrode and leading to a change in resistance. In valence change memories (VCMs) with electrode/oxide/electrode configuration, where the oxide can be insulating, such as HfO 2 , [3] TaO x , [4,5] SrTiO 3 , [6] or semiconducting, [7] such as LaMnO 3 , [8] or La 2 NiO 4 , [9][10][11] the resistance is modified by the drift of oxygen ions (or oxygen vacancies) and the concomitant local valence change of the cationic sublattice. Nonetheless, in many cases electronic and ionic effects interplay to give raise to the memristive response. [12,13] The switching event in VCMs can take place at different scales and the memories can be classified as: i) filamentary, where the change of resistance and migration of oxygen takes place in a very localized region, ii) interface-type, where the mechanism occurs at the electrode/oxide interface, [2] or iii) volume-type, which can be considered an extension of the interface-type where eventually the whole volume of the oxide is involved in the change of resistance. [14] Although so far most of the technological effort has been devoted to filamentary-type memories, these devices suffer from strong cycle-to-cycle and cell-to-cell variability. The variability has been associated to the electroforming step, and Interface-type valence change memories (VCMs) are exciting candidates for multilevel storage in resistive random access memories (RRAM) and as artificial synapses for neuromorphic computing. Several materials have been proposed as VCM candidates and, depending on the materials and electrodes of choice, different switching mechanisms take place leading to the change in resistance. Here, the focus is on La 0.8 Sr 0.2 MnO 3-δ (LSM) perovskite and, par...

Memristive Properties of Perovskite‐Based Planar Devices Redox‐based resistive random access memories (ReRAM) show great potential to improve current electronic devices' storage capabilities. In perovskites, variations in oxygen stoichiometry are directly linked to changes in resistance, governing the devices' switching characteristics. In article number 2200498, Carlos Moncasi, Mónica Burriel, and co‐workers study the memristive properties of novel perovskite‐based planar devices and obtain new insights into the key role of the films' nanostructure.