Functional electronic inversion layers at ferroelectric domain walls

Abstract

Ferroelectric domain walls hold great promise as functional 2D-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 behavior at charged walls in semiconducting ErMnO 3. 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 to the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.

Conductivity Contrast and Tunneling Charge Transport in the Vortexlike Ferroelectric Domain Patterns of Multiferroic Hexagonal YMnO3

“…From our results we conclude that the charge transport in these DWs is dominated by tunneling of the remaining localized charge carriers. Interestingly, recent electron-energy loss spectroscopy and density-functional theory calculations suggest charge transport via minority charge carriers (electrons) for the insulating DWs at sufficiently large voltage [40]. Their localized nature and small carrier density of about 0.1 per Mn ion is well consistent with the occurrence of hopping charge transport as found in the present work.…”

Infrared nano-spectroscopy of ferroelastic domain walls in hybrid improper ferroelectric Ca3Ti2O7

“…Ferroics also have naturally occurring heterogeneities in the form of domains and domain walls [8][9][10][11][12][13][14][15][16][17][18]. This is especially true for Ca 3 Ti 2 O 7 , a hybrid improper ferroelectric [19,20] where the polarization arises from a trilinear coupling mechanism [21][22][23] and abundant charged domain walls have been observed [19,20,24].…”

“…Atomic-and piezo-force imaging reveal the different orientations of directional order parameters and domain wall character, providing a physical playground for graph theory. Like other counterpart materials [16,17], ferroelectric domain walls in Ca 3 Ti 2 O 7 are anisotropic and more conducting than their surroundings -although the domains themselves are insulating [19,20,24]. Theoretical modeling and electron diffraction experiments recently revealed that polarization rotates across the ferroelectric walls in a manner that is more Néel-than Ising-like [25].…”

Unexpected Giant Microwave Conductivity in a Nominally Silent BiFeO3 Domain Wall

“…On the other hand, while mobile‐carrier conduction and bound‐charge oscillation both contribute to the ac conduction, they are fundamentally different physical processes and should be analyzed separately. It is therefore imperative to obtain a unified picture on these two mechanisms in ferroelectrics DWs, which is crucial for their applications in nanoelectronics …”