Erasable Domain Wall Current-Dominated Resistive Switching in BiFeO3 Devices with an Oxide-Metal Interface

Electrictransport in the charged domain wall (CDW) region hasemerged as a promising phenomenon for the development of next-generationferro-resistive memory with ultrahigh data storage density. However,accurately measuring the conductivity of CDWs induced by polarizationreversal remains challenging due to the polarization modulation ofthe Schottky barrier at the thin film-electrode interface,which could partially contribute to the collected oncurrent of the device. Here, we propose carefully selecting an electrodethat can suppress the effect of interfacial barrier modulation inducedby polarization reversal, allowing the collected current mainly fromthe conductive CDWs. The experiment was conducted on epitaxial BiFeO3(001) thin-film devices with vertical and horizontal geometries.Piezo-response force microscopy scanning showed the local polarizationexperienced 180 degrees rotation to form CDWs under the vertical electricfield. However, devices with SrRuO3 epitaxial top electrodesstill exhibit an interfacial barrier-dominated diode behavior, withthe on current proportional to the electrode area.To identify the CDW current, more interfacial defects were introducedby the deposition of Pt top electrodes, which significantly enhancedcharge injection for the compensation of the reversed polarizationdriven by the electric field, leading to the suppressed polarizationmodulation of the Schottky barrier height. It was observed that thecurrent flow through Pt electrodes is significantly lower comparedto that of SRO electrodes and appears to be primarily influenced bythe electrode perimeter instead of the electrode area, indicatingCDW-dominated conduction behavior in these devices. Planar nanodeviceswere further fabricated to support the quantitative investigationof the Pt electrode size-dependent on current witha linear fit of the current magnitude versus the CDW cross-sectionalarea. This work constitutes an essential part of understanding therole of the CDW current in ferro-resistive memory devices.

Automated summary

By carefully selecting an electrode that can suppress the interfacial barrier modulation induced by polarization reversal, the conductivity of charged domain walls (CDWs) in thin films can be accurately measured. This is important for the development of high-density ferro-resistive memory.