Quasi-one-dimensional metallic conduction channels in exotic ferroelectric topological defects

Abstract

Ferroelectric topological objects provide a fertile ground for exploring emerging physical properties that could potentially be utilized in future nanoelectronic devices. Here, we demonstrate quasi-one-dimensional metallic high conduction channels associated with the topological cores of quadrant vortex domain and center domain (monopole-like) states confined in high quality BiFeO3 nanoislands, abbreviated as the vortex core and the center core. We unveil via the phase-field simulation that the superfine metallic conduction channels along the center cores arise from the screening charge carriers confined at the core region, whereas the high conductance of vortex cores results from a field-induced twisted state. These conducting channels can be reversibly created and deleted by manipulating the two topological states via electric field, leading to an apparent electroresistance effect with an on/off ratio higher than 103. These results open up the possibility of utilizing these functional one-dimensional topological objects in high-density nanoelectronic devices, e.g. nonvolatile memory.

Progress on Emerging Ferroelectric Materials for Energy Harvesting, Storage and Conversion

“…[ 146 ] On the other hand, the polar topological structures offer a pathway of enhancing its electronic conductivity, as evidenced in ferroelectrics like BiFeO 3 . [ 147,148 ] Therefore, referring to the superior anti‐fatigue performance, one can see that the synergistic ionic and electronic conductivity yields close‐to‐ideal interfacial polarization screening. [ 149–151 ] Similar to Au/SrTiO 3 /LSMO capacitors, this further implies that the improved energy storage performances are assisted by electric‐field driven electrochemical activities.…”

Nonvolatile ferroelectric domain wall memory integrated on silicon

“…Further, these I-V curves reveal a relatively high-current contrast of about three orders of magnitude between OFF and ON states (ON/OFF=10 3 ) at a read bias of +4V. Such ON/OFF ratio is around the same level of DW memories grown on perovskite substrates 8,16,17,19,20,25,48 , signifying the comparable performance of our Si-based prototype as a candidate for nonvolatile memories. These results were repeatable for randomly picked spots.…”

“…Ferroelectric domain walls (DWs), the low-dimensional structures that separate differently polarized regions, have been shown to exhibit appealing properties in recent years [1][2][3][4][5] , including metallic conduction [6][7][8][9][10][11] , magnetoresistance 12 and photovoltaic behaviors [13][14][15] . Conductive DWs, mainly appearing as head-to-head (H-H) or tail-to-tail (T-T) DWs 6, 16 -19 , have been hitherto detected in various types of materials, such as proper ferroelectric perovskites 8,[16][17][18]20 , non-perovskites 10,21,22 and improper ferroelectrics 11,23,24 . Due to the nanoscale space distribution of DWs and non-destructive switching of polarization states, ferroelectric DWs hold great potentials for the applications in highdensity and low power nonvolatile memories 16,25,26 .…”

Atomic mapping of periodic dipole waves in ferroelectric oxide

“…Despite the fundamental differences between ferroelectrics and ferromagnets, the topological domains in these two ferroic materials are quite analogous. With the recent development of aberrationcorrected transmission electron microscopy (TEM), the topological domains that are well known in ferromagnets have been directly visualized at the atomic scale in ferroelectrics, such as flux closures (2,3), vortices (4-7), skyrmions (8), center-type domains (9,10), and merons (11).…”