Direct observation of delithiation as the origin of analog memristance in LixNbO2

摘要

The discovery of analog Lisubx/subNbOsub2/sub memristors revealed a promising new memristive mechanism wherein the diffusion of Lisup+/sup rather than Osup2?/sup ions enables precise control of the resistive states. However, directly correlating lithium concentration with changes to the electronic structure in active layers remains a challenge and is required to truly understand the underlying physics. Chemically delithiated single crystals of LiNbOsub2/sub present a model system for correlating lithium variation with spectroscopic signatures from operando soft x-ray spectroscopy studies of device active layers. Using electronic structure modeling of the x-ray spectroscopy of Lisubx/subNbOsub2/sub single crystals, we demonstrate that the intrinsic memristive behavior in Lisubx/subNbOsub2/sub active layers results from field-induced degenerate p-type doping. We show that electrical operation of Lisubx/subNbOsub2/sub-based memristors is viable even at marginal Li deficiency and that the analog memristive switching occurs well before the system is fully metallic. This study serves as a benchmark for material synthesis and characterization of future Lisubx/subNbOsub2/sub-based memristor devices and suggests that valence change switching is a scalable alternative that circumvents the electroforming typically required for filamentary-based memristors.