Free-electron gas at charged domain walls in insulating BaTiO3

Abstract

Hetero interfaces between metal-oxides display pronounced phenomena such as semiconductor-metal transitions, magnetoresistance, the quantum hall effect and superconductivity. Similar effects at compositionally homogeneous interfaces including ferroic domain walls are expected. Unlike hetero interfaces, domain walls can be created, displaced, annihilated and recreated inside a functioning device. Theory predicts the existence of 'strongly' charged domain walls that break polarization continuity, but are stable and conduct steadily through a quasi-two-dimensional electron gas. Here we show this phenomenon experimentally in charged domain walls of the prototypical ferroelectric BaTiO3. Their steady metallic-type conductivity, 109 times that of the parent matrix, evidence the presence of stable degenerate electron gas, thus adding mobility to functional interfaces.

Polarization Switching Ability Dependent on Multidomain Topology in a Uniaxial Organic Ferroelectric

“…Conversely, for charged domain walls to exist, the bound charges should be almost completely compensated by mobile charges and/or immobile charged defects. 4 10 and Pb(Zr,Ti)O 3 (PZT) thin films. 11 In general, an external electric field E lifts the degeneracy between ferroelectric multidomains and thus exerts pressure on the domain walls to expand preferred P domains.…”

Towards reversible control of domain wall conduction in Pb(Zr0.2Ti0.8)O3 thin films

“…In particular, electrical conductance at ferroelectric domain walls in otherwise insulating wide-bandgap (multi)ferroics such as BiFeO 3 3 has attracted much interest as a pathway towards domain-wall-based nanoelectronics. [4][5][6] The intrinsic conductance of charged domain walls 7,8 is related to the head-to-head or tail-to-tail orientation of the polarization vector, and therefore modifiable only by changes to the domain geometry itself, 9 limiting its applicability in device design. The segregation of defects such as oxygen vacancies preferentially at domain walls 10 providing states within the band gap of the ferroelectric material for localised extrinsic conduction -offers a more promising pathway.…”

Anomalous change in leakage and displacement currents after electrical poling on lead-free ferroelectric ceramics

“…In general, researchers avoid long time E-poling in the samples for piezoelectric sensors and actuators applications. [20][21][22][23][24] However, it is also true that built-in hysteresis loops are widely used to decrease hysteresis and self heating in hard piezoelectrics. 25 Takenaka group has carried out extensive studies on polarization, phase transition, dielectric and electrical properties of (1 À x)NBT-xBiAlO 3 solid solution with pre intended Al substitution at B-site.…”