Topologically Protected Ferroelectric Domain Wall Memory with Large Readout Current

The discovery and precise manipulation of atomic-size conductive ferroelectric domain defects, such as geometrically confined walls, offer new opportunities for a wide range of prospective electronic devices, and the so-called walltronics is emerging consequently. Here we demonstrate the highly stable and fatigue-resistant nonvolatile ferroelectric memory device based on deterministic creation and erasure of conductive domain wall geometrically confined inside a topological domain structure. By introducing a pair of delicately designed co-axial electrodes onto the epitaxial BiFeO3 film, one can easily create quadrant center topological polar domain structure. More importantly, a reversible switching of such center topological domain structure between the convergent state with highly conductive confined wall and the divergent state with insulating confined wall can be realized, hence resulting in an apparent resistance change with a large On/Off ratio > 104 and a technically preferred readout current (up to 40 nA). Owing to the topological robustness of the center domain structure, the device exhibits the excellent restoration repeatability over 106 cycles and a long retention over 12 days (> 106 s). This work demonstrates a good example for implementing the exotic polar topologies in high-performance nanoscale devices, and would spur more interest in exploring the rich emerging applications of these exotic topological states.