Giant switchable non thermally-activated conduction in 180° domain walls in tetragonal Pb(Zr,Ti)O3

Abstract

Conductive domain walls in ferroelectrics offer a promising concept of nanoelectronic circuits with 2D domain-wall channels playing roles of memristors or synoptic interconnections. However, domain wall conduction remains challenging to control and pA-range currents typically measured on individual walls are too low for single-channel devices. Charged domain walls show higher conductivity, but are generally unstable and difficult to create. Here, we show highly conductive and stable channels on ubiquitous 180° domain walls in the archetypical ferroelectric, tetragonal Pb(Zr,Ti)O3. These electrically erasable/rewritable channels show currents of tens of nanoamperes (200 to 400 nA/μm) at voltages ≤2 V and metallic-like non thermally-activated transport properties down to 4 K, as confirmed by nanoscopic mapping. The domain structure analysis and phase-field simulations reveal complex switching dynamics, in which the extraordinary conductivity in strained Pb(Zr,Ti)O3 films is explained by an interplay between ferroelastic a- and c-domains. This work demonstrates the potential of accessible and stable arrangements of nominally uncharged and electrically switchable domain walls for nanoelectronics.

Ferroelectric Domain Wall p–n Junctions

“…The physics responsible for generating domain-wall conduction is still under debate and the reality is that details vary from one system to another . In general, though, domain walls across which there are discontinuities in polarization (so-called “charged” walls) are most reliably seen to conduct. ,,− In such cases, conductivity scales with the magnitude of the divergence in polarization at the wall, which can often be “tuned” by changing wall orientation. ,,,, Carrier type can also be tuned: walls which support head-to-head polar discontinuities accumulate negative screening charges and show n -type transport behavior, while tail-to-tail walls accumulate positive screening charge and are found to be p -type. ,− …”