Deterministic Role of Concentration Surplus of Cation Vacancy over Anion Vacancy in Bipolar Memristive NiO

Abstract

Migration of oxygen vacancies has been proposed to play an important role in the bipolar memristive behaviors because oxygen vacancies can directly determine the local conductivity in many systems. However, a recent theoretical work demonstrated that both migration of oxygen vacancies and coexistence of cation and anion vacancies are crucial to the occurrence of bipolar memristive switching, normally observed in the small-sized NiO. So far, experimental work addressing this issue is still lacking. In this work, with conductive atomic force microscopy and combined scanning transmission electron microscopy and electron energy loss spectroscopy, we reveal that concentration surplus of Ni vacancy over O vacancy determines the bipolar memristive switching of NiO films. Our work supports the dual-defects-based model, which is of fundamental importance for understanding the memristor mechanisms beyond the well-established oxygen-vacancy-based model. Moreover, this work provides a methodology to investigate the effect of dual defects on memristive behaviors.

Electrochemically Driven Giant Resistive Switching in Perovskite Nickelates Heterostructures

“…Oxygen vacancy induced dark contrast can also be found in the low‐magnification image (see Figure S2 in the Supporting Information). The fact that low P(O 2 ) leads to more oxygen vacancies has also been reported for other oxide materials . Figure b and Figure S3 (Supporting Information) clearly show more pronounced I–V hysteresis for GdNiO 3− x films grown under lower P(O 2 ), suggesting that oxygen vacancies in GdNiO 3− x films play a crucial role in the RS behavior.…”

“…Introducing oxygen vacancies www.advelectronicmat.de microscope (STEM) results confirm that the concentration of oxygen vacancies is higher in GdNiO 3−x films deposited under lower P(O 2 ). [13,[19][20][21][22] Figure 1b and Figure S3 (Supporting Information) clearly show more pronounced I-V hysteresis for GdNiO 3−x films grown under lower P(O 2 ), suggesting that oxygen vacancies in GdNiO 3−x films play a crucial role in the RS behavior. The good epitaxial relationship between GdNiO 3−x and Nb-SrTiO 3 can be observed in both films.…”

Self‐Assembled NiO Nanocrystal Arrays as Memristive Elements

“…This effect can also be observed on the study of the thickness dependent resistive switching in the NiO film or when the I-V is measured at different height of the nanocrystals. [33,34] We also notice that in our NiO film the V S is 2.7 V, meaning that the memristive element of NiO can be activated with the bias application of higher than 2.5 V, which is also been reported in other NiO-based resistive switching devices in both film [34][35][36][37] and nanostructure [38][39][40][41][42][43] forms. This is also in agreement with our previous results that the correlation between the I-V and electrochemical strain mapping (ESM) loop with the frequency shifts are substantially stronger at higher switching bias.…”

Oxygen Vacancy Engineering for Highly Tunable Ferromagnetic Properties: A Case of SrRuO3 Ultrathin Film with a SrTiO3 Capping Layer

“…According to previous reports, these line profiles strongly suggest the existence of high‐density V O . [ 21,37–41 ] Therefore, our STEM‐ABF results confirm that the STO capping layer grown at P (O 2 ) STO = 5 mTorr can induce high‐density V O in the SRO layer underneath and meanwhile keep the layer from noticeable Ru vacancies.…”