Ferroelectric domain walls hold great promise as functional two-dimensional materials because of their unusual electronic properties. Particularly intriguing are the so-called charged walls where a polarity mismatch causes local, diverging electrostatic potentials requiring charge compensation and hence a change in the electronic structure. These walls can exhibit significantly enhanced conductivity and serve as a circuit path. The development of all-domain-wall devices, however, also requires walls with controllable output to emulate electronic nano-components such as diodes and transistors. Here we demonstrate electric-field control of the electronic transport at ferroelectric domain walls. We reversibly switch from resistive to conductive behaviour at charged walls in semiconducting ErMnO3. We relate the transition to the formation—and eventual activation—of an inversion layer that acts as the channel for the charge transport. The findings provide new insight into the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.
We thank M. Fiebig for direct financial support and scientific input, and M. Trassin and A. Kaiser for fruitful discussions. We thank HZB for the allocation of synchrotron beam time and we gratefully acknowledge financial support by HZB. D.M., J.S. and N.A.S. acknowledge funding from the ETH Zurich and the SNF (proposal no. 200021_149192, D.M. and J.S.), the Alexander von Humboldt Foundation (D.M.) and the ERC Advanced Grant programme (grant number 291151, N.A.S.). Electron microscopy research at Cornell (J.A.M., M.E.H., D.A.M. and D.G.S.) was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award no. DE-SC0002334. This work made use of the electron microscopy facility of the Cornell Center for Materials Research (CCMR) with support from the National Science Foundation Materials Research Science and Engineering Centers (MRSEC) programme (DMR-1120296) and NSF IMR-0417392. We gratefully acknowledge the use of facilities with the LeRoy Eyring Center for Solid State Science at Arizona State University and assistance from J. Mardinly and T. Aoki. J.A.M. acknowledges financial support from the Army Research Office in the form of a National Defense Science & Engineering Graduate Fellowship and from the National Science Foundation in the form of a National Science Foundation Graduate Research Fellowship. M.S. was supported by MINECO-Spain through Grants No. FIS2013-48668-C2-2-P and No. SEV-2015-0496, and Generalitat de Catalunya (2014 SGR301). E.B. and Z.Y. were supported in part by the US Department of Energy and carried out at the Lawrence Berkeley National Laboratory under Contract No. DE-AC02-05CH11231.