Abstract
The mechanism of the electric-pulse induced resistance change effect in Au/Pr0.65Ca0.35MnO3/SrTi0.99Nb0.01O3 thin-film samples is studied by means of in situ electrical stimulation inside a transmission electron microscope. A detailed equivalent-circuit model analysis of the measured current-voltage characteristics provides crucial information for the proper interpretation of the microscopy results. The electrical transport data of the electron-transparent samples used for the in situ investigations is verified by comparison to measurements of unpatterned thin-film samples. We find comprehensive evidence for electrochemical oxygen vacancy migration affecting the potential barrier of the pn junction between Pr0.65Ca0.35MnO3 and SrTi0.99Nb0.01O3 as well as the resistance of the manganite bulk. The high-resistance state formation in the Pr0.65Ca0.35MnO3 bulk is frequently accompanied by structural transformations, namely detwinning and superstructure formation, most likely as the result of the joint impact of dynamic charge inhomogenities by oxygen vacancy migration and injection of high carrier densities at the electrodes.
Highlights
IntroductionSince the discovery of the electric-pulse induced resistance change effect (EPIR) in Pr0.7Ca0.3MnO3,1 nonvolatile resistive switching has been revealed in a variety of complex transitionmetal oxide based devices.[2,3] Due to the demonstrated fast switching between well de ned high- and low-resistance states (HRS, LRS) in capacitor-like devices, this class of materials is among the candidates for the resistance random access memory (ReRAM) concept being explored as an alternative to the contemporary ash memory.[4,5,6,7]
Resistive switching in Au/PCMO/STNO thin- lm heterostructures was studied by means of in situ transmission electron microscopy (TEM) and equivalentcircuit model analysis
The electrical transport properties of both electron-transparent cross-section samples used for in situ TEM and unpatterned reference samples prove to be basically identical, namely rectifying current–voltage characteristics due to the PCMO/STNO pn junction with forward currents being limited by the series resistance of the manganite lm and its interface to the Au top electrode
Summary
Since the discovery of the electric-pulse induced resistance change effect (EPIR) in Pr0.7Ca0.3MnO3,1 nonvolatile resistive switching has been revealed in a variety of complex transitionmetal oxide based devices.[2,3] Due to the demonstrated fast switching between well de ned high- and low-resistance states (HRS, LRS) in capacitor-like devices, this class of materials is among the candidates for the resistance random access memory (ReRAM) concept being explored as an alternative to the contemporary ash memory.[4,5,6,7] In this contribution, we address the question of the switching mechanism in Au/Pr0.65Ca0.35MnO3 (PCMO) based thin- lm samples by means of in situ transmission electron microscopy (TEM). We present and discuss the results of the in situ TEM investigations
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