An Oxygen Vacancy Memristor Ruled by Electron Correlations

Abstract

Resistive switching effects offer new opportunities in the field of conventional memories as well as in the booming area of neuromorphic computing. Here the authors demonstrate memristive switching effects produced by a redox‐driven oxygen exchange in tunnel junctions based on NdNiO3, a strongly correlated electron system characterized by the presence of a metal‐to‐insulator transition (MIT). Strikingly, a strong interplay exists between the MIT and the redox mechanism, which on the one hand modifies the MIT itself, and on the other hand radically affects the tunnel resistance switching and the resistance states' lifetime. That results in a very unique temperature behavior and endows the junctions with multiple degrees of freedom. The obtained results bring up fundamental questions on the interplay between electronic correlations and the creation and mobility of oxygen vacancies in nickelates, opening a new avenue toward mimicking neuromorphic functions by exploiting the electric‐field control of correlated states.

Memristive effects in YBa2Cu3O7-x devices with transistor-like structure

“…The reversible switching of the conductance between ON, OFF and intermediate non-volatile states (figure 3) can be explained by an interfacial redox reaction between aluminium and YBCO, similar to the memristive effects observed in YBCO/MoSi [43], NdNiO 3 /MoSi [46] and YBCO/ITO [45] micro junctions. The redox reaction naturally reduces the material with a higher reduction potential (here YBCO, given the high reduction potential of copper E • (Cu) = 2.4 eV) and oxidizes the material with a lower reduction potential (E • (Al) = −1.676 eV) [47].…”

“…A different approach to electrically control the fundamental state of a cuprate consists of placing it in contact with a second material with low reduction potential such as YBa 2 Cu 3 O 7−δ (YBCO). This system yields an interfacial redox reaction that can be reversibly controlled by applying voltage pulses of different polarity and amplitude [40][41][42][43][44]. This way, it is possible to drive oxygen in and out of the cuprate at will, which ultimately allows for the reversible switching of its transport and superconducting properties.…”

Strain-Induced Uphill Hydrogen Distribution in Perovskite Oxide Films

“…Ionic control of transition-metal oxides (TMOs) has become an effective pathway to tune functionalities including magnetic, − electronic, − optical, − thermoelectric, , and catalytic performances. − As the smallest ion, H + (proton) is naturally endowed with high mobility, excellent reversibility, prominent modulation effect, and broad applicability to binary and complex oxides. − In recent years, increasing efforts have been put into developing facile hydrogenation methods − and discovering novel properties in protonated phases. − Owing to the tight relationship between hydrogen (doping) concentration, lattice, and electronic structure, understanding the migration mechanism and detecting the spatial distribution of H + are necessary for finely tailoring the physical properties on a microscopic scale and enhancing the reaction efficiency of the energy-conversion process in protonic ceramic fuel cells. ,,− A typical example is the construction of reconfigurable NdNiO 3 electronic devices (artificial neurons, synapses, and memory capacitors) via the sensitivity of electronic properties to the local distribution of H + …”

Nanoelectronics Using Metal–Insulator Transition

“…implemented the behavior of memristors by fabricating junctions with amorphous MoSi alloy on nickelate NNO thin films. [ 229 ] In this study, the movement of oxygen ions driven by the electric field resulted in giant tunnel electrical resistances. The high resistance state was achieved through a spontaneous redox reaction at the interface of the corresponding junction, where the interfacial NNO was reduced and MoSi was oxidized, forming a tunnel barrier.…”