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

Abstract

Electric transport in the charged domain wall (CDW) region has emerged as a promising phenomenon for the development of next-generation ferro-resistive memory with ultrahigh data storage density. However, accurately measuring the conductivity of CDWs induced by polarization reversal remains challenging due to the polarization modulation of the Schottky barrier at the thin film−electrode interface, which could partially contribute to the collected "on" current of the device. Here, we propose carefully selecting an electrode that can suppress the effect of interfacial barrier modulation induced by polarization reversal, allowing the collected current mainly from the conductive CDWs. The experiment was conducted on epitaxial BiFeO 3 (001) thin-film devices with vertical and horizontal geometries. Piezo-response force microscopy scanning showed the local polarization experienced 180°rotation to form CDWs under the vertical electric field. However, devices with SrRuO 3 epitaxial top electrodes still exhibit an interfacial barrierdominated diode behavior, with the "on" current proportional to the electrode area. To identify the CDW current, more interfacial defects were introduced by the deposition of Pt top electrodes, which significantly enhanced charge injection for the compensation of the reversed polarization driven by the electric field, leading to the suppressed polarization modulation of the Schottky barrier height. It was observed that the current flow through Pt electrodes is significantly lower compared to that of SRO electrodes and appears to be primarily influenced by the electrode perimeter instead of the electrode area, indicating CDW-dominated conduction behavior in these devices. Planar nanodevices were further fabricated to support the quantitative investigation of the Pt electrode size-dependent "on" current with a linear fit of the current magnitude versus the CDW cross-sectional area. This work constitutes an essential part of understanding the role of the CDW current in ferro-resistive memory devices.

Modeling a domain wall network in BiFeO3 with stochastic geometry and entropy-based similarity measure

“…Their non-trivial electronic and transport properties have been demonstrated to be suitable for new applications of domain wall nanoelectronics (Catalan et al, 2012;Meier and Selbach, 2022). DWs can also provide memristive features (Maksymovych et al, 2011;Chen et al, 2023;Liu et al, 2023). In particular, both DWs' enhanced conductivity with respect to domains (Chiu et al, 2011;Farokhipoor and Noheda, 2011;2012) and DWs' memristive behavior (Rieck et al, 2022) have been observed in as-grown self-assembled ferroelectric-ferroelastic DW networks where conduction is "lateral, " i.e., the charge flows parallel to the surface through the DW network from wall to wall.…”