  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.
